Devices, systems and methods to detect viable infectious agents in a fluid sample and susceptibility of infectious agents to anti-infectives

ABSTRACT

Various devices, systems and methods for detecting infectious agents or determining a susceptibility of an infectious agent to an anti-infective are described herein. One example method comprises introducing a fluid sample to a surface; exposing the surface to a solution; sampling the solution after exposing the solution to the surface; and detecting a change in an electrical characteristic of a sensing device exposed to the solution sampled corresponding to a presence of the infectious agent in the fluid sample.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/482,307 filed on Apr. 7, 2017, now U.S. Pat. No. 10,174,356, whichclaims the benefit of U.S. Provisional Application No. 62/343,564 filedon May 31, 2016, the contents of which are incorporated herein byreference in their entireties.

FIELD OF THE INVENTION

The present disclosure relates generally to in vitro detection ofinfectious agents and in vitro determination of the susceptibility ofinfectious agents to anti-infectives. More specifically, the presentdisclosure relates to devices, systems, and methods to detect viableinfectious agents in a fluid sample and determine the susceptibility ofsuch infectious agents to anti-infectives.

BACKGROUND

Infections caused by anti-infective resistant infectious agents ormicrobes are a significant problem for healthcare professionals inhospitals, nursing homes, and other healthcare environments. Forexample, such infections can lead to a potentially life-threateningcomplication known as sepsis where chemicals released into thebloodstream by an infectious agent can trigger a dangerous whole-bodyinflammatory response as well as a vasoactive response causing fever,low blood pressure, and possibly death. When faced with such aninfection, a preferred course of action is for a clinician to useanti-infective compounds judiciously, preferably only those necessary toalleviate the infection. However, what occurs most frequently today isthat until the organism is identified and tested for drug sensitivity,broad-spectrum anti-infectives, often multiple drugs, are given to thepatient to ensure adequacy of treatment. This tends to result inmultiple drug-resistant infectious agents. Ideally, the sensitivity ofthe infectious agent would be detected soon after its presence isidentified. The present disclosure presents devices, systems, andmethods for accomplishing this goal.

Existing methods and instruments used to detect anti-infectiveresistance in infectious agents include costly and labor intensivemicrobial culturing techniques to isolate the infectious agent andinclude tests such as agar disk diffusion or broth microdilution whereanti-infectives are introduced as liquid suspensions, paper disks, ordried gradients on agar media. However, those methods require manualinterpretation by skilled personnel and are prone to technical orclinician error.

While automated inspection of such panels or media can reduce thelikelihood of clinician error, current instruments used to conduct theseinspections are often costly and require constant maintenance. Inaddition, current instruments often rely on an optical read-out of theinvestigated samples requiring bulky detection equipment and access topower supplies. Most importantly, these methods require days to obtain aresult, as the infectious agents must reproduce several times indifferent media prior to being exposed to the anti-infective todetermine their susceptibility.

In addition, such methods and instruments often cannot conduct suchtests directly on a patient's bodily fluids and require lengthy samplepreparation times.

As a result of the above limitations and restrictions, there is a needfor improved devices, systems, and methods to quickly and effectivelydetect anti-infective resistant infectious agents in a patient sample.

SUMMARY

Various devices, systems and methods for detecting viable infectiousagents in a fluid sample and determining the susceptibility of suchinfectious agents to anti-infectives are described herein. In oneembodiment, a method of detecting an infectious agent in a fluid samplecan include introducing a fluid sample to a surface; exposing thesurface to a solution; sampling the solution after exposing the solutionto the surface; and detecting a change in an electrical characteristicof a sensing device exposed to the solution sampled corresponding to apresence of the infectious agent in the fluid sample.

In another embodiment, a method of assessing a susceptibility of aninfectious agent to an anti-infective can include introducing a fluidsample to a first surface and a second surface; exposing the firstsurface comprising the infectious agent to a first solution; exposingthe second surface comprising the infectious agent to a second solution,wherein at least one of the second surface and the second solutioncomprises an anti-infective; sampling the first solution after exposingthe first solution to the first surface; sampling the second solutionafter exposing the second solution to the second surface; monitoring afirst electrical characteristic of a first sensing device exposed to thefirst solution sampled; monitoring a second electrical characteristic ofa second sensing device exposed to the second solution sampled; andcomparing the first electrical characteristic and the second electricalcharacteristic to assess the susceptibility of the infectious agent tothe anti-infective.

In yet another embodiment, a method of assessing a susceptibility of aninfectious agent to an anti-infective includes introducing a fluidsample to a first surface and a second surface; exposing the firstsurface comprising the infectious agent to a first solution; exposingthe second surface comprising the infectious agent to a second solution,wherein at least one of the second surface and the second solutioncomprises an anti-infective; sampling the first solution after exposingthe first surface to the first solution; sampling the second solutionafter exposing the second surface to the second solution; monitoring afirst electrical characteristic of a sensing device exposed to the firstsolution sampled; monitoring a second electrical characteristic of thesensing device exposed to the second solution sampled; and comparing thefirst electrical characteristic and the second electrical characteristicto assess the susceptibility of the infectious agent to theanti-infective.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 illustrates one embodiment of a system for detecting infectiousagents in a fluid sample.

FIG. 2A illustrates a side view of an embodiment of an electrochemicalcell having an external reference electrode.

FIG. 2B illustrates a side view of an embodiment of an electrochemicalcell having an on-chip reference electrode.

FIG. 3A illustrates a side view of an embodiment of an electrochemicalcell having an external reference electrode and a power source.

FIG. 3B illustrates a side view of an embodiment of an electrochemicalcell having an on-chip reference electrode and a power source.

FIG. 4 illustrates an example readout from an analyzer or readerconnected or communicatively coupled to the electrochemical cell.

FIG. 5 illustrates another embodiment of a system for detectinginfectious agents in a fluid sample.

FIG. 6A illustrates a side view of an embodiment of an electrochemicalsensor of the system.

FIG. 6B illustrates a side view of another embodiment of anelectrochemical sensor of the system.

FIG. 7 illustrates an example readout from an analyzer or readerconnected or communicatively coupled to the glucose sensor.

FIG. 8 illustrates yet another embodiment of a system for detectinginfectious agents in a fluid sample.

FIG. 9 illustrates a side view of an embodiment of a light-addressablepotentiometric (LAP) sensor of the system.

FIG. 10 illustrates an example readout from an analyzer or readerconnected or communicatively coupled to the LAP sensor.

FIG. 11A illustrates one embodiment of a system for determining thesusceptibility of an infectious agent to one or more anti-infectives.

FIG. 11B illustrates a variation of the system from FIG. 11A usingelectrochemical cells.

FIG. 11C illustrates another variation of the system from FIG. 11A usingglucose sensors.

FIG. 11D illustrates another variation of the system from FIG. 11A usingLAP sensors.

FIG. 12 illustrates one embodiment of a method for detecting infectiousagents in a fluid sample.

FIG. 13 illustrates one embodiment of a method for detecting infectiousagents in a fluid sample.

FIG. 14 illustrates another embodiment of a method for detectinginfectious agents in a fluid sample.

FIG. 15 illustrates an embodiment of a method for detecting asusceptibility of an infectious agent to one or more anti-infectives.

FIG. 16 illustrates another embodiment of a method for determining thesusceptibility of an infectious agent to one or more anti-infectives.

DETAILED DESCRIPTION

Variations of the devices, systems, and methods described herein arebest understood from the detailed description when read in conjunctionwith the accompanying drawings. It is emphasized that, according tocommon practice, the various features of the drawings may not be toscale. On the contrary, the dimensions of the various features may bearbitrarily expanded or reduced for clarity and not all features may bevisible or labeled in every drawing. The drawings are taken forillustrative purposes only and are not intended to define or limit thescope of the claims to that which is shown.

FIG. 1 illustrates an embodiment of a system 100 for detecting aninfectious agent 102 in a fluid sample 124. In one embodiment, thesystem 100 can comprise a fluid delivery device 106, a filter housing108 containing a filter 110, a sensing device 116, and a parameteranalyzer 114. The sensing device 116 can be located on a substrate 112.

The substrate 112 can be comprised of a polymer or polymeric material, ametal, a ceramic, a semiconductor layer, an oxide layer, an insulator,or a combination thereof. As shown in FIG. 1, the parameter analyzer 114can be integrated into one device with the sensing device 116. Forexample, the parameter analyzer 114 can be fabricated on the samesubstrate 112 as the sensing device 116. In other embodiments, theparameter analyzer 114 can be a standalone unit or device coupled to thesensing device 116. The sensing device will be discussed in more detailin the sections that follow.

In some instances, the fluid sample 124 can comprise the infectiousagent 102. The fluid sample 124 can include a bodily fluid such asblood, serum, plasma, urine, saliva, joint fluid, semen, wound material,spinal fluid, mucus, or a combination thereof. In other embodiments, thefluid sample 124 can also include an environmental fluid such as liquidssampled from a stream, river, lake, ocean, contamination site,quarantine zone, or emergency area. The fluid sample 124 can also be afood sample.

The infectious agent 102 can be any metabolizing single ormulti-cellular organism including a bacteria or fungus. The infectiousagent 102 can also be a virus or a prion. In certain embodiments, theinfectious agent 102 can be a bacteria selected from the generacomprising of, but not limited to, Acinetobacter, Aeromonas, Bacillus,Bacteroides, Citrobacter, Enterobacter, Escherichia, Klebsiella,Morganella, Pandoraea, Proteus, Providencia, Pseudomonas, Ralstonia,Raoultella, Salmonella, Serratia, Shewanella, Shigella,Stenotrophomonas, Streptomyces, Staphylococcus, Enterococcus,Clostridium or any combination thereof. In other embodiments, theinfectious agent 102 can be a fungus selected from the genera comprisingof, but not limited to, Candida, Cryptococcus, or any combinationthereof. In another embodiment, the infectious agent 102 can includeamoeba. In further embodiments, the infectious agent 102 can be cancercells.

As illustrated in FIG. 1, the fluid delivery device 106 can deliver orinject the fluid sample 124 into the filter housing 108 in step 1A. Inone embodiment, the fluid delivery device 106 can be a pump. Forexample, the fluid delivery device 106 can be a hydraulic pump, apneumatic pump, a syringe pump, or a combination thereof. In otherembodiments, the fluid delivery device 106 can be an injectioncartridge, a microfluidic channel, a pipette, a reaction tube, acapillary, a test tube, a combination thereof, or a portion therein.

The filter housing 108 can be a container or vessel configured to secureor enclose the filter 110. For example, the filter housing 108 can be aprotective chamber. The protective chamber can be an electricallyisolated environment. The protective chamber can also be a temperaturecontrolled chamber, a light controlled chamber, or a combinationthereof.

The filter 110 can have a filter surface 126. The filter 110 can trap orisolate the infectious agent 102 by depositing or delivering theinfectious agent 102 onto the filter surface 126. The filter surface 126can be an external surface, an internal surface extending into thefilter 110, or a combination thereof. The filter 110 can be made of, butis not limited to, cellulose acetate, regenerated cellulose, nylon,polystyrene, polyvinylidene fluoride (PVDF), polyethersulfone (PES),polytetrafluorethylene (PTFE), glass microfiber, or a combinationthereof.

In one embodiment, the filter 110 can have filter pores of sequentiallysmaller pore size. For example, the filter 110 can have larger filterpores at the top of the filter and progressively smaller filter porestoward the bottom of the filter. In another embodiment, the filter 110can have filter pores of a similar pore size throughout the entirefilter. In these embodiments, the filter surface 126 can be the surfaceof the pores. In another embodiment, the filter 110 can be a mesh ormatrix structure and the filter surface 126 can be a mesh or matrixsurface.

The filter 110 can be a non-clogging filter such as a high-capacityfilter. Although not shown in FIG. 1, it is contemplated by thisdisclosure that the filter 110 can refer to a plurality of filters in astacked arrangement.

The filter 110 can comprise, carry, or hold the infectious agent 102when a fluid sample 124 comprising or carrying an infectious agent 102is introduced to the filter 110. For example, the fluid sample 124 canbe introduced to the filter 110 when the fluid sample 124 is poured overor injected through the filter 110. The filter 110 can isolate orseparate the infectious agent 102 or other molecules or cells from thesupernatant of the fluid sample 124.

The filter housing 108 can have at least one opening which allows fluidor supernatant from the fluid sample 124 to evacuate the filter housing108. For example, step 1A can include the additional step of discardingthe fluid or supernatant from the fluid sample 124 through the openingafter isolating the infectious agent 102 on the filter surface 126.

One advantage of the methods and systems 100 disclosed herein is theseparation of any suspected or potential infectious agents 102 from thesensing device 116, the parameter analyzer 114, or a combinationthereof. For example, the filter 110, the filter surface 126, the filterhousing 108, or a combination thereof can prevent any suspected orpotential infectious agents 102 from contacting any portion of thesensing device 116, the parameter analyzer 114, or a combinationthereof. The filter 110, the filter surface 126, the filter housing 108,or a combination thereof can trap or isolate any suspected or potentialinfectious agents 102 on the filter surface 126 or in the filter housing108.

In an alternative embodiment not shown in FIG. 1, a stimulus solutioncan be added to the fluid sample 124 before introducing the fluid sample124 to the filter 110. The stimulus solution can be a nutrient or growthsolution. The stimulus solution can be a super nutrient solution.

The fluid sample 124 can also be pre-filtered in a step before step 1A.This pre-filtering step can involve filtering the fluid sample 124 usingan additional filter, a microfluidic filter, or a combination thereof tofilter out other larger cellular components including blood cells orepithelial cells from the fluid sample 124 when the fluid sample 124 iscomposed of bodily fluid.

The same fluid delivery device 106 or another fluid delivery device 106can also be used to deliver or inject a nutrient solution 130 to thefilter housing 108 in step 1B. The fluid delivery device 106 cancontinuously or periodically expose the filter surface 126 to thenutrient solution 130.

After exposing the filter 110 to the nutrient solution 130, the filter110 can be heated to a temperature of between 30° C. and 40° C. andallowed to incubate for an incubation period 132 in step 1C. In oneembodiment, the filter 110 can be incubated while in the filter housing108. In another embodiment, the filter 110 can be removed from thefilter housing 108 prior to incubation. In some embodiments, the filter110 can be incubated with the nutrient solution 130. In someembodiments, the incubation period 132 can range from 15 minutes to overone hour. In other embodiments, the incubation period 132 can be lessthan 15 minutes. The incubation period 132 can be adjusted based on thetype of infectious agent 102 suspected in the fluid sample 124, such asthe type of bacteria, fungus, virus, or prion.

The incubation period 132 can also be adjusted based on the suspectedamount of the infectious agent 102 present in the fluid sample 124, theamount or volume of the fluid sample 124, or a combination thereof. Forexample, the incubation period 132 can be increased when the suspectedamount of the infectious agent 102 or the volume of the fluid sample 124is below a threshold amount. The filter 110 can be allowed to incubatewith the nutrient solution 130 in order to promote the proliferation ofthe suspected infectious agent 102 on the filter surface 126. Oneadvantage of incubating the filter 110 is to increase the sensitivity ofthe system 100 to small amounts of the suspected infectious agent 102.For example, incubating the filter 110 can allow the system 100 toreduce its level of detection.

After incubating the filter 110, the effluent or outflow of the nutrientsolution 130 exposed to the filter 110 can be sampled. The effluent oroutflow of the nutrient solution 130 exposed to the filter 110 can bereferred to as the sample effluent 134.

In an alternative embodiment not shown in FIG. 1 but contemplated bythis disclosure, the infectious agent 102 can be removed from the filterhousing 108 by centrifugation or by filtration. For example, theinfectious agent 102 can be removed from the filter housing 108 usinganother filter such as a syringe filter. The sample effluent 134 orsupernatant after this filtration step can be collected and the solutioncharacteristic of this sample effluent 134 can be analyzed.

The sample effluent 134 can be analyzed by a sensing device 116. In oneembodiment, the sample effluent 134 can be analyzed by applying orintroducing an aliquot of the sample effluent 134 to the sensing device116 in step 1D(a). In another embodiment, the sample effluent 134 can beanalyzed by inserting a portion of the sensing device 116 directly intothe sample effluent 134 in step 1D(b).

The sample effluent 134 can comprise a solution characteristic. Thesolution characteristic can refer to one or more attributes of thesolution making up the sample effluent 134. For example, the solutioncharacteristic can include a concentration of a solute, an absolutenumber or molecular count of solutes in solution, a solutiontemperature, or a combination thereof. For example, the solutioncharacteristic can refer to the amount or concentration of ions, organicmolecules such as amino acids, vitamins or glucose, minerals, or otherinorganic compounds in the sample effluent 134.

The solution characteristic can vary as a result of changes due to theenergy use, growth, and metabolism of an infectious agent 102 in thefluid sample 124. For example, the solution characteristic can be adirect or indirect byproduct of a cellular activity undertaken by theinfectious agent 102 such as cell metabolism or cell growth. Thesolution characteristic can vary as a result of ions, organic molecules,or minerals produced by, consumed by, or otherwise attributed to theinfectious agent 102. For example, the solution characteristic canchange as a result of an amount or concentration of nutrients insolution consumed or depleted by the infectious agent 102.

In one embodiment, the sample effluent 134 can comprise hydrogen ions(H⁺) as a byproduct of bacterial cell metabolism or growth. In otherembodiments, the sample effluent 134 can comprise adenosine triphosphate(ATP), carbon dioxide (CO₂), lactic acid, carbonic acid, nitrates (NO₃⁻), or a combination thereof produced by or attributed to an infectiousagent 102.

A change in the solution characteristic can cause a change in theelectrical characteristic of the sensing device 116. The parameteranalyzer 114 can detect a change in the electrical characteristic (seeFIG. 4) of the sensing device 116 exposed to the sample effluent 134. Inone embodiment, the parameter analyzer 114 can be a voltage meter. Inother embodiments, the parameter analyzer 114 can be, but is not limitedto, a multimeter, a source meter, an ammeter, a capacitance analyzer, ora combination thereof.

The electrical characteristic can include, but is not limited to, avoltage, an impedance, a current, a capacitance, a resistance, aresonant frequency, a noise level, a level of induction, or acombination thereof measured at or near the sensing device 116. Thechange in the electrical characteristic can include, but is not limitedto, a voltage change, an impedance change, a current change, acapacitance change, a resistance change, a change in resonant frequency,a noise level change, an induction change, or a combination thereofmeasured at or near the sensing device 116.

As shown in FIG. 1, the parameter analyzer 114 can be fabricated on thesame substrate 112 as the sensing device 116. In other embodiments, theparameter analyzer 114 can be a standalone unit or meter coupled to thesensing device 116. The parameter analyzer 114 can also be connected toor communicatively coupled to a display 113 or display componentconfigured to provide a result of the detection or a read-out of theelectrical characteristic of the sensing device 116. In certainembodiments, the parameter analyzer 114 can be a mobile device, ahandheld device, a tablet device, or a computing device such as a laptopor desktop computer and the display 113 can be a mobile device display,a handheld device display, a tablet display, or a laptop or desktopmonitor.

In one embodiment, the parameter analyzer 114 can display a resultindicating the presence of an infectious agent 102 in the fluid sample124 via the display 113 of the parameter analyzer 114. In anotherembodiment, the parameter analyzer 114 can wirelessly communicate aresult indicating the presence of an infectious agent 102 in the fluidsample 124 to a computing device having the display 113.

The parameter analyzer 114, a reader, or a combination thereof candetect a change in the electrical characteristic of the sensing device116 exposed to the sample effluent 134 corresponding to the presence ofthe infectious agent 102 in the fluid sample 124 introduced to thesystem 100 in step 1A.

The steps depicted in FIG. 1 do not require the particular order shownto achieve the desired result and certain steps or processes may occurin parallel.

FIG. 2A illustrates a side cross-sectional view of one embodiment of thesensing device 116. The sensing device 116 can be an electrochemicalcell comprising an external reference electrode 202, an electrolyte 204or electrically conducting solution retained by container walls 206, afunctionalization layer 208, a conductor layer 210, and a substratelayer 212. The sensing device 116 can be connected or coupled to theparameter analyzer 114. The parameter analyzer 114 can be coupled toboth the external reference electrode 202 and the conductor layer 210.

As shown in FIG. 2A, the external reference electrode 202 can extendinto the electrolyte 204. In one embodiment, the electrolyte 204 can bethe sample effluent 134. In other embodiments, the electrolyte 204 cancomprise portions of the fluid sample 124.

The external reference electrode 202 can be used to apply a knownpotential to the electrolyte 204, which can be detected by the sensingdevice 116. The external reference electrode 202 can have a stable andwell-known internal voltage and can act as a differential noise filterfor removing electrical noise from measurements taken by the sensor. Thesystem 100 can use the external reference electrode 202 to determine orrecord a relative change in the electrical characteristic of the sensingdevice 116 rather than having to ascertain an absolute change. Thesystem 100 can also use the external reference electrode 202 todetermine or record a relative difference between the electricalcharacteristics of multiple sensing devices 116. In one embodiment, theexternal reference electrode 202 can be a standalone probe or electrode.In other embodiments, the external reference electrode 202 can becoupled to the parameter analyzer 114 or a reader connected to theparameter analyzer 114. The parameter analyzer 114 can also be used toapply a voltage to the external reference electrode 202.

In one embodiment, the external reference electrode 202 can be asilver/silver chloride (Ag/AgCl) electrode. In other embodiments, theexternal reference electrode 202 can be, but is not limited to, asaturated calomel reference electrode (SCE) or a copper-copper (II)sulfate electrode (CSE). Since metals or other materials used tofabricate such external reference electrodes can often have aninhibitory or harmful effect on the infectious agents 102 underinvestigation, one advantage of the methods, devices, and systems 100disclosed herein is the separation of the infectious agent 102 from thecomponents of the system 100 in physical or fluid contact with theseexternal reference electrodes.

The substrate layer 210 can be composed of, but is not limited to, anynon-conducting material such as a polymer, an oxide, a ceramic, or acomposite thereof. As depicted in FIG. 2A, the conductor layer 210 canbe disposed on or cover the substrate layer 212.

The conductor layer 210 can be composed of, but is not limited to, ametal, a semiconducting material, a metal/metal-salt, or a combinationthereof. For example, the conductor layer 210 can be composed of, but isnot limited to, silicon, gold, silver, aluminum, platinum, or acomposite thereof. The conductor layer 210 can also be an organicsemiconductor, a carbon nanotube, graphene, an organic conductor such asthose derived from polyacetylene, polyaniline, Quinacridone,Poly(3,4-ethylenedioxythiophene) or PEDOT, PEDOT: polystyrene sulfonate(PSS), or a combination thereof. The conductor layer 210 can be composedof any conducting material which allows an electrical property change tobe measured, including, but is not limited to, a voltage change and/or acurrent change measured through the conductor layer 210, thefunctionalization layer 208, and the electrolyte 204 to the externalreference electrode 202.

As depicted in FIG. 2A, the functionalization layer 208 can be disposedon or cover the conductor layer 210. The functionalization layer 208 cancomprise silanes, DNA, proteins, antibodies, self-assembled mono layers(SAMs), oxides, buffered hydrogels, PVC, parylene, polyACE, or any otherbiochemically active materials. The functionalization layer 208 can beconfigured to facilitate the sensing device 116 from interacting withions, analytes, or other molecules or byproducts in the electrolyte 204.For example, the functionalization layer 208 can be a pH-sensitivelayer.

In one example, the functionalization layer 208 can comprise hydroxylgroups which can interact with hydrogen ions (H±) in the electrolyte204. This interaction can generate a change in the electricalcharacteristic of the sensing device 116 detected by the parameteranalyzer 114. In one embodiment, this interaction can create ameasurable change in the electrical characteristic of the sensing device116 at the interface between the electrolyte 204/functionalization layer208 or the interface between the electrolyte 204/conductor layer 210.

For example, the parameter analyzer 114 can be a voltmeter and thevoltmeter can detect a voltage change (ΔV) at or near thefunctionalization layer 208 exposed to the electrolyte 204. The voltagechange can be determined with respect to the external referenceelectrode 202 extending into or in contact with the electrolyte 204. Inthis embodiment, the functionalization layer 208 and the conductor layer210 can be considered part of a working or active electrode of thesystem 100.

To obtain a dynamic sensor response, the sensing device 116 can also beoperated, in some instances, in a constant voltage mode or constantcapacitance mode in one or more embodiments. When the sensing device 116is operated in a constant voltage mode, the voltage can be set a fixedvalue (e.g., a flat-band voltage) and the voltage shift (ΔV) thatresults from the surface potential generated at the interface of theelectrolyte 204/conductor layer 210 or the electrolyte204/functionalization layer 208 can be directly recorded.

As depicted in FIG. 2A, the electrolyte 204, the functionalization layer208, and the conductor layer 210 can be surrounded by a container wall206. The container wall 206 can be made of an inert or non-conductivematerial. The container wall 206 can hold or retain the electrolyte 204or be responsible for delivering or introducing the sample effluent 134to the sensing device 116.

FIG. 2B illustrates a side cross-sectional view of another embodiment ofthe sensing device 116. In this embodiment, the sensing device 116comprises a working electrode 214 and an on-chip reference electrode216. In this embodiment, the working electrode 214 and the on-chipreference electrode 216 can be disposed on the same substrate layer 212.The substrate layer 212 can be composed of the same material as thesubstrate layer 212 depicted in FIG. 2A.

The electrolyte 204 can flow over or be exposed to both the workingelectrode 214 and the on-chip reference electrode 216 simultaneously. Inthis embodiment, the working electrode 214 and the on-chip referenceelectrode 216 can be separated by a container wall 214 or containerdivide.

The working electrode 214 can comprise the functionalization layer 208disposed on or covering the conductor layer 210. The functionalizationlayer 218 can comprise silanes, DNA, proteins, antibodies, oxides,self-assembled mono layers (SAMs), buffered hydrogels, PVC, parylene,polyACE, or any other biochemically active materials.

As shown in FIG. 2B, a passivation layer 218 can be disposed on or coverthe conductor layer 210. The passivation layer 218 can be configured toprevent the on-chip reference electrode 216 from interacting withanalytes, ions, or other molecules or byproducts in the electrolyte 204.For example, the passivation layer 218 can be a pH-insensitive layer.The passivation layer 218 can comprise silanes, self-assembledmonolayers (SAMs), buffered hydrogels, parylene, polyACE, or any otherbiochemically inert material.

In this embodiment, the parameter analyzer 114 can have a leadconnection wire, such as a copper wire, connected to the conductor layer210 of the working electrode 214 and another lead connection wireconnected to the conductor layer 210 of the on-chip reference electrode216.

In this and other embodiments, the sensing device 116 shown in FIG. 2Bminiaturizes the sensor set-up shown in FIG. 2A. The on-chip referenceelectrode 216 obviates the need for an external reference electrode,such as the external reference electrode 202. The passivation layer 218of the on-chip reference electrode 216 prevents the conductor layer 210covered by the passivation layer 218 from interacting with the ions,analytes, or other molecules or byproducts in the electrolyte 204. Thisallows a reader or another device from being able to differentiate theelectrical signals obtained by the parameter analyzer 114.

In one embodiment, the conductor layer 210 can be a metal covered with ametal salt such as a metal chloride. For example, the conductor layer210 can be a silver/silver chloride contact. In this embodiment, theconductor layer 210 can be covered by a passivation layer 218 such as aKCL electrolyte gel, to prevent the conductor layer 210 from interactingwith analytes, ions, or other molecules or byproducts in the electrolyte204 and to act as a reference electrode.

Since metals or other materials used to fabricate such on-chip referenceelectrodes 216 can often have an inhibitory or harmful effect on theinfectious agents 102 under investigation, one advantage of the methods,devices, and systems 100 disclosed herein is the separation of theinfectious agent 102 from the components of the system 100 in physicalor fluid contact with these on-chip reference electrodes 216.

FIG. 3A illustrates a side cross-sectional view of an embodiment of thesensing device 116 of FIG. 2A having a power source 220. The powersource 220 can apply a DC or AC voltage (usually in the range of +/−5V)to the conductor layer 210 and the external reference electrode via thefunctionalization layer 208 and the electrolyte 204. This voltage canalso be set to be used as a working point.

Depending on the concentration or amount of analytes, ions, molecules,or cellular byproducts present in the electrolyte 202, a change in theelectrical characteristic (e.g., a horizontal shift (ΔV) of the voltagemeasurement curve) will occur as the analytes, ions, molecules, orcellular byproducts interact with the sensing device 116. This changecan be measured by the parameter analyzer 114. In one embodiment, when avoltage is applied over time or when different electrolyte 202 solutionsare introduced to the sensing device 116, the analytes, ions, molecules,or cellular byproducts can interact with the functionalization layer208, causing an additional electrical characteristic change, which canalso be detected by the parameter analyzer 114.

FIG. 3B illustrates a side cross-sectional view of an embodiment of thesensing device 116 of FIG. 2B having a power source 220. The powersource 220 can apply a DC or AC voltage (usually in the range of +/−5V)between the conductor layer 210 of the working electrode 214, throughthe electrolyte 202 and the conductor layer 210 of the on-chip referenceelectrode 216. This setup can be a miniaturized form of the sensingdevice 116 of FIG. 3A. This voltage can also be set to be used as aworking point. Depending on the concentration or amount of analytes,ions, molecules, or cellular byproducts present in the electrolyte 202,a change in the electrical characteristic, e.g. a horizontal shift (ΔV)of the voltage measurement curve, can occur, as the analytes, ions,molecules, or cellular byproducts interact with the sensing device 116.This change can be measured by the parameter analyzer 114. In oneconfiguration, when a voltage is applied over time or when differentelectrolytes 202 are introduced to the sensing device 116, the analytes,ions, molecules, or cellular byproducts can interact with thefunctionalization layer 208, causing an additional electricalcharacteristic change that can be detected by the parameter analyzer114.

In another embodiment, a potential can be applied between the workingelectrode 214 through the electrolyte 204 to the on-chip referenceelectrode 216. The parameter analyzer 114 can then record a current,which flows between the two electrodes. Depending on the concentrationor amount of analytes, ions, chemicals, molecules, or cellularbyproducts present in the electrolyte 202, a change of the electricalcharacteristics (in this case, a shifting of the current measurementcurve (AI)) can occur, as the analytes, ions, molecules, or cellularbyproducts interact with the electrolyte 202 or the sensing device 116.

FIG. 4 illustrates one example of an output/voltage curve generatedbased on readings obtained from the parameter analyzer 114. As can beseen in the output/voltage curve, the difference between the solutioncharacteristics of two electrolyte 204 solutions or the electrolyte 204solution over time can be measured by the change in the voltage (ΔV). Inone embodiment, the output can be obtained when a constant voltage isapplied to the system. The electrical output can include, but is notlimited to, a current, a voltage, an impedance, a capacitance, and aresistance. In one example, the hydroxyl groups of functionalizationlayer 208 can interact with the hydrogen ions (H⁺) in the electrolyte204. This can create an additional voltage/potential or capacitance at,for example, the interface between the functionalization layer 208 andthe electrolyte 204 or the conductor layer 210 and the electrolyte 204.This additional voltage will alter the output/voltage curve or theoverall electrical characteristic of the sensing device 116. To obtain adynamic sensor response, the sensing device 116 can also be operated ina constant output mode. In this constant output mode, the electricaloutput, such as a voltage or current, can be set at a fixed value (e.g.,a flat-band current or voltage) and the voltage shift (ΔV) that resultsfrom the surface potential generated at the interface of the electrolyte204 and functionalization layer 208 can be directly recorded.

FIG. 5 illustrates another embodiment of a system 100 for detecting aninfectious agent 102 in a fluid sample 124. In one embodiment, thesystem 100 can comprise the fluid delivery device 106, the filterhousing 108 containing the filter 110, a sensing device 500, and theparameter analyzer 114.

As shown in FIG. 5, the parameter analyzer 114 can be integrated intoone device with the sensing device 500. For example, the parameteranalyzer 114 can be fabricated on the same substrate 112 as the sensingdevice 500. In other embodiments, the parameter analyzer 114 can be astandalone unit or device coupled to the sensing device 500.

As illustrated in FIG. 5, the fluid delivery device 106 can deliver orinject the fluid sample 124 into the filter housing 108 in step 5A. Thefluid delivery device 106, the filter housing 108, the filter 110, andthe filter surface 126 can be the same fluid delivery device 106, thesame filter housing 108, the same filter 110, and the same filtersurface 126, respectively, depicted in FIG. 1.

The filter housing 108 can have at least one opening which allows fluidor supernatant from the fluid sample 124 to evacuate the filter housing108. For example, step 5A can include the additional step of discardingthe fluid or supernatant from the fluid sample 124 through the openingafter isolating the infectious agent 102 on the filter surface 126.

One advantage of the methods and systems 100 disclosed herein is theseparation of any suspected or potential infectious agents 102 from thesensing device 500, the parameter analyzer 114, or a combinationthereof. For example, the filter 110, the filter surface 126, the filterhousing 108, or a combination thereof can prevent any suspected orpotential infectious agents 102 from contacting any portion of thesensing device 500, the parameter analyzer 114, or a combinationthereof.

In an alternative embodiment not shown in FIG. 5, a stimulus solutioncan be added to the fluid sample 124 before introducing the fluid sample124 to the filter 110. The stimulus solution can be a nutrient or growthsolution. The stimulus solution can be a super nutrient solution.

The fluid sample 124 can also be pre-filtered in a step before step 5A.This pre-filtering step can involve filtering the fluid sample 124 usingan additional filter, a microfluidic filter, or a combination thereof tofilter out other larger cellular components including blood cells orepithelial cells from the fluid sample 124 when the fluid sample 124 iscomposed of bodily fluid.

The same fluid delivery device 106 or another fluid delivery device 106can also be used to deliver or inject a nutrient solution 130 to thefilter housing 108 in step 5B. The fluid delivery device 106 cancontinuously or periodically expose the filter surface 126 to thenutrient solution 130.

After exposing the filter 110 to the nutrient solution 130, anotherfluid delivery device 106 can be used to deliver or inject a knownconcentration of glucose 502 to the filter housing 108 or the filter 110in step 5C. For example, 20 mM or 360 mg/dl of glucose can be deliveredor injected to the filter housing 108.

The filter housing 108 can be heated to a temperature of between 30° C.and 40° C. and allowed to incubate for an incubation period 132 in step5D. In one embodiment, the filter 110 can be incubated while in thefilter housing 108. In another embodiment, the filter 110 can be removedfrom the filter housing 108 prior to incubation. In some embodiments,the filter 110 can be incubated with the known concentration of glucose502. In other embodiments, the filter 110 can be incubated with theknown concentration of glucose 502 and the nutrient solution 130. Insome embodiments, the incubation period 132 can range from one hour tofive hours. In other embodiments, the incubation period 132 can be morethan five hours. In further embodiments, the incubation period 132 canbe less than one hour. The incubation period 132 can be adjusted basedon the type of infectious agent 102 suspected in the fluid sample 124,such as the type of bacteria, fungus, virus, or prion.

The incubation period 132 can also be adjusted based on the suspectedamount of the infectious agent 102 present in the fluid sample 124, theamount or volume of the fluid sample 124, the amount of glucose 502added, or a combination thereof. For example, the incubation period 132can be increased when the suspected amount of the infectious agent 102or the volume of the fluid sample 124 is below a threshold amount. Thefilter 110 can be allowed to incubate with the nutrient solution 130 inorder to promote the proliferation of the suspected infectious agent 102on the filter surface 126.

One advantage of incubating the filter 110 is to increase thesensitivity of the system 100 to small amounts of the suspectedinfectious agent 102. For example, incubating the filter 110 can allowthe system 100 to reduce its level of detection.

After incubating the filter 110, the effluent or outflow of the nutrientsolution 130 and/or the solution of glucose 502 exposed to the filter110 can be sampled. The effluent or outflow of the nutrient solution 130and/or the solution of glucose 502 exposed to the filter 110 can bereferred to as the sample effluent 504.

The sample effluent 504 can be analyzed by the sensing device 500. Inthe example embodiment shown in FIG. 5, the sensing device 500 can be aglucose sensor. The glucose sensor will be discussed in more detailbelow.

In one embodiment, the sample effluent 504 can be analyzed by applyingor introducing an aliquot of the sample effluent 504 to the sensingdevice 500 in step 5E(a). In another embodiment, the sample effluent 504can be analyzed by inserting a portion of the sensing device 500directly into the sample effluent 504 in step 5E(b). In yet anotherembodiment, the sample effluent 504 can be analyzed by inserting asensing device 500 having both a glucose sensor and another sensor 506directly into the sample effluent 504 in step 5E(c). The other sensor506 can include the sensing device 116 such as the electrochemical cellof FIG. 2A, 2B, 3A or 3B or a light-addressable potentiometric (LAP)sensor.

In an alternative embodiment not shown in FIG. 5 but contemplated bythis disclosure, the infectious agent 102 can be removed from the filterhousing 108 by centrifugation or by filtration. For example, theinfectious agent 102 can be removed from the filter housing 108 using afilter such as a syringe filter. The sample effluent 504 or supernatantafter this filtration step can be collected and the solutioncharacteristic, including the glucose concentration, of this sampleeffluent 504 can be analyzed by a glucose sensor serving as the sensingdevice 500. In all such embodiments, the infectious agent 102 isseparated from the sample effluent 504 under analysis.

In one embodiment, the glucose sensor and the other sensor 506 can befabricated on the same substrate 112 or test-strip. In this and otherembodiments, the glucose sensor can be one component of a multisensoryhaving the other sensor 506 as another component.

The sample effluent 504 can comprise a solution characteristic. Thesolution characteristic can refer to one or more attributes of thesolution making up the sample effluent 504. In some embodiments, thesolution characteristic can include a concentration of glucose, anabsolute number or molecular count of glucose, or a combination thereof.In other embodiments, the solution characteristic can include aconcentration of a byproduct of glucose metabolism or glucoseproduction, an absolute number or molecular count of such a byproduct, asolution temperature, or a combination thereof. For example, thesolution characteristic can change as a result of a change in the knownconcentration of the glucose solution 502 added to the system 100 instep 5C.

The solution characteristic can vary as a result of changes due to theenergy use, growth, and metabolism of the infectious agent 102 isolatedor trapped by the filter 110. For example, the solution characteristiccan be a direct or indirect byproduct of a cellular activity undertakenby the infectious agent 102 such as cell metabolism or cell growth. Thesolution characteristic can vary as a result of glucose or othermolecules or ions produced or consumed by the infectious agent 102 onthe filter surface 126.

A change in the solution characteristic can cause a change in theelectrical characteristic of the sensing device 500. The parameteranalyzer 114 can detect a change in an electrical characteristic (seeFIG. 7) of the sensing device 500 exposed to the sample effluent 504.The parameter analyzer 114 can be, but is not limited to, a voltmeter, amultimeter, an ammeter, a capacitance analyzer, or a combinationthereof.

The electrical characteristic can include, but is not limited to, avoltage, an impedance, a current, a capacitance, a resistance, aresonant frequency, a noise level, a level of induction, or acombination thereof measured at or near the sensing device 500. Thechange in the electrical characteristic can include, but is not limitedto, a voltage change, an impedance change, a current change, acapacitance change, a resistance change, a change in resonant frequency,a noise level change, an induction change, or a combination thereofmeasured at or near the sensing device 500.

As shown in FIG. 5, the parameter analyzer 114 can be fabricated on thesame substrate 112 as the sensing device 500. In other embodiments, theparameter analyzer 114 can be a standalone unit or meter coupled to thesensing device 500. The parameter analyzer 114 can also be connected toor communicatively coupled to the display 113 or display componentconfigured to provide a result of the detection or a read-out of theelectrical characteristic of the sensing device 500. In certainembodiments, the parameter analyzer 114 can be a mobile device, ahandheld device, a tablet device, or a computing device such as a laptopor desktop computer and the display 113 can be a mobile device display,a handheld device display, a tablet display, or a laptop or desktopmonitor.

In one embodiment, the parameter analyzer 114 can display a resultindicating the presence of an infectious agent 102 in the fluid sample124 via the display 113 of the parameter analyzer 114. In anotherembodiment, the parameter analyzer 114 can wirelessly communicate aresult indicating the presence of an infectious agent 102 in the fluidsample 124 to a computing device having the display 113.

The parameter analyzer 114, a reader, or a combination thereof candetect a change in the electrical characteristic of the sensing device500 exposed to the sample effluent 504 corresponding to the presence ofthe infectious agent 102 in the system 100. The steps depicted in FIG. 5do not require the particular order shown to achieve the desired resultand certain steps or processes may occur in parallel.

FIG. 6A illustrates a side cross-sectional view of an embodiment of thesensing device 500. In one embodiment, the sensing device 500 can be anelectrochemical sensing device (e.g., a glucose sensing device). In thisembodiment, the sensing device 500 comprises a working electrode 600, areference electrode 602, and a counter electrode 604. The workingelectrode 600, the reference electrode 602, and the counter electrode604 can be disposed on the same substrate layer 606. The substrate layer606 can be composed of, but is not limited to, any non-conductingmaterial such as a polymer, an oxide, a ceramic, or a composite thereof.For example, the substrate layer 606 can be composed of the samematerial as the substrate layer 212 depicted in FIG. 2A.

The electrolyte 204 can flow over or be exposed to the working electrode600, the reference electrode 602, and the counter electrode 604simultaneously. As depicted in FIG. 6, the electrolyte 204 can besurrounded by the container wall 206. The container wall 206 can be madeof an inert or non-conductive material. The container wall 206 can holdor retain the electrolyte 204 or be responsible for delivering orintroducing the sample effluent 504 to the sensing device 500.

The sensing device 500 can be connected to a voltmeter 608 and anammeter 610 or any other meter or measurement device. The voltmeter 608can have one lead connection wire, such as a copper wire, connected tothe working electrode 600 and another lead connection wire connected tothe reference electrode 602. The ammeter 610 can also have one leadconnection wire connected to the reference electrode 602 and anotherlead connection wire connected to the counter electrode 604.

FIG. 6B illustrates a side cross-sectional view of another embodiment ofthe sensing device 500. The sensing device 500 of FIG. 6B can be a twoelectrode setup where the reference electrode 602 can also act as acounter electrode. In this embodiment, a voltage can be applied betweenthe reference electrode 602 and the working electrode 600. At the sametime, the current flowing from the reference electrode 602 through theelectrolyte 204 to the working electrode 600 can be measured. To detecta given analyte, molecule, ion, or DNA, a known chemical or solution canbe added to the electrolyte 204. This chemical can react with the targetanalytes, ions, molecules or cellular byproducts, altering the currentcurve of FIG. 7. In one example embodiment, the oxidation of glucose togluconolactone or gluconic acid (catalyzed, for example, by glucoseoxidase) can be measured. In another reaction, glucose dehydrogenase canbe used as an enzyme. Additional chemicals can also be added to generatean electrical current that can be measured by the system. The totalcharge passing through the electrodes can be proportional to the amountof glucose in the solution that has reacted with the enzyme.

FIG. 7 illustrates one example of a current/voltage curve generatedbased on readings obtained from the voltmeter 609 and the ammeter 610connected to the sensing device 500. As can be seen in thecurrent/voltage curve, the difference between the solutioncharacteristics of two electrolyte 204 solutions or the electrolyte 204solution over time can be measured by the change in the voltage (ΔV) ata constant current. To obtain a dynamic sensor response, the sensingdevice 500 can also be operated in a constant voltage mode. In thisconstant voltage mode, a fixed voltage can be applied between theelectrodes and a current can be recorded. Different concentrations ofthe target analytes, ions, molecules, or cellular byproducts can resultin different current outputs. In another embodiment, a current can befixed between the two electrodes while the voltage is recorded. In thisembodiment, the current change (ΔI) can be measured over time at thefixed voltage.

FIG. 8 illustrates another embodiment of a system 100 for detecting aninfectious agent 102 in a fluid sample 124. In one embodiment, thesystem 100 can comprise the fluid delivery device 106, the filterhousing 108 containing the filter 110, a sensing device 800, and theparameter analyzer 114.

As shown in FIG. 8, the parameter analyzer 114 can be integrated intoone device with the sensing device 800. For example, the parameteranalyzer 114 can be fabricated on the same substrate 112 as the sensingdevice 800. In other embodiments, the parameter analyzer 114 can be astandalone unit or device coupled to the sensing device 800.

As illustrated in FIG. 8, the fluid delivery device 106 can deliver orinject the fluid sample 124 into the filter housing 108 in step 8A. Thefluid delivery device 106, the filter housing 108, the filter 110, andthe filter surface 126 can be the same fluid delivery device 106, thesame filter housing 108, the same filter 110, and the same filtersurface 126, respectively, depicted in FIG. 1.

The filter housing 108 can have at least one opening which allows fluidor supernatant from the fluid sample 124 to evacuate the filter housing108. For example, step 8A can include the additional step of discardingthe fluid or supernatant from the fluid sample 124 through the openingafter isolating the infectious agent 102 on the filter surface 126.

One advantage of the methods and systems 100 disclosed herein is theseparation of any suspected or potential infectious agents 102 from thesensing device 800, the parameter analyzer 114, or a combinationthereof. For example, the filter 110, the filter surface 126, the filterhousing 108, or a combination thereof can prevent any suspected orpotential infectious agents 102 from contacting any portion of thesensing device 800, the parameter analyzer 114, or a combinationthereof.

In an alternative embodiment not shown in FIG. 8, a stimulus solutioncan be added to the fluid sample 124 before introducing the fluid sample124 to the filter 110. The stimulus solution can be a nutrient or growthsolution. The stimulus solution can be a super nutrient solution.

The fluid sample 124 can also be pre-filtered in a step before step 8A.This pre-filtering step can involve filtering the fluid sample 124 usingan additional filter, a microfluidic filter, or a combination thereof tofilter out other larger cellular components including blood cells orepithelial cells from the fluid sample 124 when the fluid sample 124 iscomposed of bodily fluid.

The same fluid delivery device 106 or another fluid delivery device 106can also be used to deliver or inject a nutrient solution 130 to thefilter housing 108 in step 8B. The fluid delivery device 106 cancontinuously or periodically expose the filter surface 126 to thenutrient solution 130.

After exposing the filter 110 to the nutrient solution 130, the filterhousing 108 can be heated to a temperature of between 30° C. and 40° C.and allowed to incubate for an incubation period 132 in step 8C. In oneembodiment, the filter 110 can be incubated while in the filter housing108. In another embodiment, the filter 110 can be removed from thefilter housing 108 prior to incubation. In some embodiments, the filter110 can be incubated with the nutrient solution 130. The incubationperiod 132 can range from 15 minutes to over one hour. In otherembodiments, the incubation period 132 can be less than 15 minutes. Theincubation period 132 can be adjusted based on the type of infectiousagent 102 suspected in the fluid sample 124, such as the type ofbacteria, fungus, virus, or prion.

The incubation period 132 can also be adjusted based on the suspectedamount of the infectious agent 102 present in the fluid sample 124, theamount or volume of the fluid sample 124, or a combination thereof. Forexample, the incubation period 132 can be increased when the suspectedamount of the infectious agent 102 or the volume of the fluid sample 124is below a threshold amount. The filter 110 can be allowed to incubatewith the nutrient solution 130 in order to promote the proliferation ofthe suspected infectious agent 102 on the filter surface 126. Oneadvantage of incubating the filter 110 is to increase the sensitivity ofthe system 100 to small amounts of the suspected infectious agent 102.For example, incubating the filter 110 can allow the system 100 toreduce its level of detection.

After incubating the filter 110, the effluent or outflow of the nutrientsolution 130 exposed to the filter 110 can be sampled. The effluent oroutflow of the nutrient solution 130 exposed to the filter 110 can bereferred to as the sample effluent 134.

In an alternative embodiment not shown in FIG. 8 but contemplated bythis disclosure, the infectious agent 102 can be removed from the filterhousing 108 by centrifugation or by filtration. For example, theinfectious agent 102 can be removed from the filter housing 108 usinganother filter such as a syringe filter. The sample effluent 134 orsupernatant after this filtration step can be collected and the solutioncharacteristic of this sample effluent 134 can be analyzed.

The sample effluent 134 can be analyzed by the sensing device 800. Inthe example embodiment shown in FIG. 8, the sensing device 800 can be alight-addressable potentiometric (LAP) sensor. The LAP sensor will bediscussed in more detail below.

In one embodiment, the sample effluent 134 can be analyzed by applyingor introducing an aliquot of the sample effluent 134 to the sensingdevice 800 in step 8D(a). Step 8D(a) can also involve using a lightsource 804 to direct light 802 of a predetermined wavelength at thesensing device 800. The light source 804 can be a modulated lightsource. The light source 804 can be or include, but is not limited to, afocused laser beam, a light bulb, a light-emitting diode (LED), anorganic LED (OLED), a liquid crystal display (LCD), or a combinationthereof. In another embodiment, the sample effluent 134 can be analyzedby inserting a portion of the sensing device 800 directly into thesample effluent 134 in step 8D(b). Step 8D(b) can also involve using thelight source 804 to direct light 802 of a predetermined wavelength atthe sensing device 800.

The sample effluent 134 can comprise a solution characteristic. Thesolution characteristic can refer to one or more attributes of thesolution making up the sample effluent 134. In some embodiments, thesolution characteristic can include a concentration of an analyte,molecule, or ion, an absolute number or molecular count of an analyte,molecule, or ion, or a combination thereof. In other embodiments, thesolution characteristic can include a solution temperature. The solutioncharacteristic can vary as a result of changes due to the energy use,growth, and metabolism of the infectious agent 102 isolated or trappedby the filter 110. For example, the solution characteristic can be adirect or indirect byproduct of a cellular activity undertaken by theinfectious agent 102 such as cell metabolism or cell growth. Thesolution characteristic can vary as a result of molecules or ionsproduced or consumed by the infectious agent 102.

A change in the solution characteristic can cause a change in theelectrical characteristic of the sensing device 800. The parameteranalyzer 114 can detect a change in an electrical characteristic (seeFIG. 10) of the sensing device 800 exposed to the sample effluent 134.The parameter analyzer 114 can include, but is not limited to, anycombination of a voltmeter, a multimeter, or an ammeter. For example,the parameter analyzer 114 in this embodiment can include the voltagesource 908 and the ammeter 910 depicted in FIG. 9).

The electrical characteristic can include, but is not limited to, avoltage, a current, a photocurrent, or a combination thereof measured ator near the sensing device 800. The change in the electricalcharacteristic can include, but is not limited to, a voltage change, acurrent change, a photocurrent change, or a combination thereof measuredat or near the sensing device 800.

As shown in FIG. 8, the parameter analyzer 114 can be fabricated on thesame substrate 112 as the sensing device 800. In other embodiments, theparameter analyzer 114 can be a standalone unit or meter coupled to thesensing device 800. The parameter analyzer 114 can also be connected toor communicatively coupled to the display 113 or display componentconfigured to provide a result of the detection or a read-out of theelectrical characteristic of the sensing device 800. In certainembodiments, the parameter analyzer 114 can be a mobile device, ahandheld device, a tablet device, or a computing device such as a laptopor desktop computer and the display 113 can be a mobile device display,a handheld device display, a tablet display, or a laptop or desktopmonitor.

In one embodiment, the parameter analyzer 114 can display a resultindicating the presence of an infectious agent 102 in the fluid sample124 via the display 113 of the parameter analyzer 114. In anotherembodiment, the parameter analyzer 114 can wirelessly communicate aresult indicating the presence of an infectious agent 102 in the fluidsample 124 to a computing device having the display 113.

The parameter analyzer 114, a reader, or a combination thereof candetect a change in the electrical characteristic of the sensing device800 exposed to the sample effluent 134 corresponding to the presence ofthe infectious agent 102 in the system 100.

The steps depicted in FIG. 8 do not require the particular order shownto achieve the desired result and certain steps or processes may occurin parallel.

FIG. 9 illustrates a side cross-sectional view of one embodiment of thesensing device 800. In one embodiment, the sensing device 800 can be aphotocurrent sensor such as a light-addressable potentiometric (LAP)sensor. The sensing device 800 can comprise an external referenceelectrode 900, an electrolyte 204 or electrically conducting solutionretained by container walls 206, a functionalization layer 902, aninsulator layer 904, and a semiconductor layer 906. The sensing device800 can be connected or coupled to a voltage source 908 and an ammeter910. The voltage source 908 can be connected in series with the ammeter910, for example, with one lead connection wire connected to thesemiconductor layer 906 and the other lead connection wire connected tothe external reference electrode 900.

As depicted in FIG. 9, the electrolyte 204 and the functionalizationlayer 902 can be surrounded by a container wall 206. The container wall206 can be made of an inert or non-conductive material. The containerwall 206 can hold or retain the electrolyte 204 or be responsible fordelivering or introducing the sample effluent 134 to the sensing device800.

As shown in FIG. 9, the external reference electrode 900 can extend intothe electrolyte 204. In one embodiment, the electrolyte 204 can be thesample effluent 134. In other embodiments, the electrolyte 204 cancomprise portions of the fluid sample 124.

The voltage source 908 can apply a known potential to the sensing device800 through the external reference electrode 900. This voltage can be,but is not limited to, a DC or AC voltage. In one embodiment, theexternal reference electrode 900 can be a silver/silver chloride(Ag/AgCl) electrode. In other embodiments, the external referenceelectrode 202 can be a saturated calomel reference electrode (SCE) or acopper-copper (II) sulfate electrode (CSE).

Since metals or other materials used to fabricate such externalreference electrodes can often have an inhibitory or harmful effect onthe infectious agents 102 under investigation, one advantage of themethods, devices, and systems 100 disclosed herein is the separation ofthe infectious agent 102 from the components of the system 100 inphysical or fluid contact with these external reference electrodes.

The sensing device 800 can comprise the insulator layer 904 disposed onor covering the semiconductor layer 906. The semiconductor layer 906 canbe a layer of doped semiconducting material. The semiconductor layer 906can be composed of, but is not limited to, a layer of doped silicon. Thesemiconductor layer 906 can also be made of an organic semiconductor, acarbon nanotube, graphene, an organic conductor such as those derivedfrom polyacetylene, polyaniline, Quinacridone,Poly(3,4-ethylenedioxythiophene) or PEDOT, PEDOT: polystyrene sulfonate(PSS), or a combination thereof.

The insulator layer 904 (which can also be referred to as an isolatorlayer) can be a high-k dielectric layer or a material layer having ahigh dielectric constant (k). For example, the insulator layer 904 cancomprise aluminum oxide, hafnium oxide, titanium oxide, zirconium oxide,yttrium oxide, tantalum oxide, hafnium silicate, zirconium silicate,silicon nitride, aluminum nitride, hafnium nitride, zirconium nitride,or a combination thereof. As a more specific example, the insulatorlayer 904 can comprise aluminum dioxide, hafnium dioxide, zirconiumdioxide, or a combination thereof. In other embodiments, the insulatorlayer 216 can comprise a silicon dioxide layer.

As depicted in FIG. 9, the functionalization layer 902 can be disposedon or cover the insulator layer 904. The functionalization layer 902 cancomprise silanes, DNA, proteins, antibodies, self-assembled mono layers(SAMs), buffered hydrogels, PVC, parylene, polyACE, or any otherbiochemically active materials. The functionalization layer 902 can beconfigured to facilitate the sensing device 800 from interacting withions, analytes, or other molecules or byproducts in the electrolyte 204.For example, the functionalization layer 902 can be a pH-sensitivelayer. In one example, the functionalization layer 902 can comprisehydroxyl groups which can interact with hydrogen ions (H⁺) in theelectrolyte 204. In another embodiment, an insulator layer 904 made ofan oxide can be used as the functionalization layer 902.

An external DC bias voltage can be applied. When the light source 804(e.g., a modulated light pointer or source) illuminates the bulksilicon, light-induced charge carriers can be separated by an internalelectric field and a photocurrent can be detected by a peripheralcircuit. The amplitude of the photocurrent can depend on the localsurface potential.

The light source 804 can direct light 802 of specific wavelengths at thedoped semiconductor layer 906. When the semiconducting material, such assilicon, in the semiconductor layer 906 absorbs light 802 matching itsexcitation frequency, electron-hole pairs are generated in the bulk ofthe semiconductor layer 906 and electrons move to the interface betweenthe semiconductor layer 906 and the insulator layer 904 or thefunctionalization layer 902. As a result, a transient photocurrent canbe detected by the ammeter 910. The light source 804 can modulate thewavelengths of the light 802 directed at the semiconductor layer 906 inorder to induce an alternating current (AC) photocurrent.

The voltage source 908 can apply a bias voltage to the electrolyte 204via the external reference electrode 900. This bias voltage can beapplied between the semiconductor layer 906 and the reference electrode900. The bias voltage can be set so as to repel electrons from the dopedsemiconductor layer 906 to form a depletion layer. The bias voltage canbe set so as to repel the electrons moving to the interface between thesemiconductor layer 906 and the insulator layer 904 due to the light 802directed at the semiconductor layer 906. At a low enough bias voltage,the depletion layer is not formed. At a large enough bias voltage, thephotocurrent increases until reaching a limiting value.

A bias voltage is needed to form the depletion layer. The depletionlayer can, in turn, assist in the generation of a photocurrent. In theembodiment depicted in FIG. 9, the light intensity of the light source804 is fixed so the amplitude of the photocurrent depends on the biasvoltage applied. In addition, sensing the amplitude of the photocurrentdepends on the local surface potential. This potential is coupled to thebias voltage applied to the sensing device 800. For example, a largerconcentration of H⁺ ions provides a larger value of this potentialdifference, causing the I-V curve to shift along the bias voltage axisof FIG. 10. When the bias voltage is kept constant, a change in thephotocurrent can indicate a change in the pH of the electrolyte 204.

Since the bias voltage is in series with the potential at the interfacebetween the functionalization layer 902 and the electrolyte 204, achange in the solution characteristic of the electrolyte (such as achange in analyte concentration or pH change) can change the biasvoltage needed to maintain the constant photocurrent detected by theammeter 910. For example, hydrogen ions in the solution can interactwith the hydroxyl groups of the functionalization layer 902 and generatean additional potential change at the interface. This additional voltagewill also cause a shift in the photocurrent, comparable to increasing ordecreasing the bias voltage. In addition, hydrogen ions in the solutioncan also interact with the insulator layer 904 to generate a potentialchange at the interface and cause a shift in the photocurrent.

As shown in FIG. 8, the light source 804 can be focused so as to directlight 804 of a specific wavelength at a specific portion of thesemiconductor layer 906. Moreover, a different light source or the samelight source 804 can direct light 804 of a different wavelength at adifferent portion of the semiconductor layer 906. This allows facilemultiplexing by creating a series of different sensing areas on onephotocurrent sensor such that different areas of the sensor can beallocated for or dedicated to a different analyte, ion, or molecule.

FIG. 10 illustrates one example of a photocurrent/voltage curvegenerated based on readings obtained from the voltage source 908 and theammeter 910 connected to the sensing device 800. As can be seen in thephotocurrent/voltage curve, a change in the solution characteristic ofthe electrolyte 204 over time or the difference between the solutioncharacteristics of two different electrolytes 204 can be measured by thechange in the voltage (ΔV) at a constant photocurrent.

FIG. 11A illustrates an embodiment of a system 1100 for assessing asusceptibility of an infectious agent 102 to an anti-infective 104. Inone embodiment, the system 1100 can comprise a fluid delivery device106, a first filter housing 108A containing a first filter 110A, asecond filter housing 108B containing a second filter 110B, and aplurality of sensing devices. The sensing devices will be discussed inmore detail in the sections that follow.

The system 1100 can detect or assess the level of susceptibility of theinfectious agent 102 to the anti-infective 104. In some instances, thefluid sample 124 can comprise the infectious agent 102. The fluid sample124 can include a bodily fluid such as blood, serum, plasma, urine,saliva, joint fluid, semen, wound material, spinal fluid, mucus, or acombination thereof. In other embodiments, the fluid sample 124 can alsoinclude an environmental fluid such as liquids sampled from a stream,river, lake, ocean, contamination site, quarantine zone, or emergencyarea. The fluid sample 124 can also be a food sample.

The infectious agent 102 can be any metabolizing single ormulti-cellular organism including a bacteria or fungus. The infectiousagent 102 can also be a virus or a prion. In certain embodiments, theinfectious agent 102 can be a bacteria selected from the generacomprising of, but not limited to, Acinetobacter, Aeromonas, Bacillus,Bacteroides, Citrobacter, Enterobacter, Escherichia, Klebsiella,Morganella, Pandoraea, Proteus, Providencia, Pseudomonas, Ralstonia,Raoultella, Salmonella, Serratia, Shewanella, Shigella,Stenotrophomonas, Streptomyces, Staphylococcus, Enterococcus,Clostridium or any combination thereof. In other embodiments, theinfectious agent 102 can be a fungus selected from the genera comprisingof, but not limited to, Candida, Cryptococcus, or any combinationthereof. In another embodiment, the infectious agent 102 can includeamoeba. In further embodiments, the infectious agent 102 can be cancercells and the anti-infectives 104 can be chemotherapeutics or othercancer treatments.

As illustrated in FIG. 11A, the fluid delivery device 106 can deliver orinject the fluid sample 124 into the first filter housing 108A and thesecond filter housing 108B in step 11A. The fluid delivery device 106can be a pump. For example, the fluid delivery device 106 can be ahydraulic pump, a pneumatic pump, a syringe pump, or a combinationthereof. In other embodiments, the fluid delivery device 106 can be aninjection cartridge, a microfluidic channel, a pipette, a reaction tube,a capillary, a test tube, a combination thereof, or a portion therein.

The first filter housing 108A or the second filter housing 108B can be acontainer or vessel configured to secure or enclose the first filter110A or the second filter 110B, respectively. For example, the firstfilter housing 108A or the second filter housing 108B can be aprotective chamber. The protective chamber can be an electricallyisolated environment. The protective chamber can also be a temperaturecontrolled chamber, a light controlled chamber, or a combinationthereof.

The first filter 110A can have a first filter surface 126A and thesecond filter 110B can have a second filter surface 126B. The firstfilter 110A or the second filter 110B can trap or isolate the infectiousagent 102 by depositing or delivering the infectious agent 102 on to thefirst filter surface 126A or the second filter surface 126B,respectively. The first filter 110A or the second filter 110B can be anexternal surface, an internal surface extending into the filter, or acombination thereof. The first filter 110A or the second filter 110B canbe made from, but is not limited to, cellulose acetate, regeneratedcellulose, nylon, polystyrene, polyvinylidene fluoride (PVDF),polyethersulfone (PES), polytetrafluorethylene (PTFE), glass microfiber,or a combination thereof.

The first filter 110A or the second filter 110B can have filter pores ofsequentially smaller pore size. For example, the first filter 110A orthe second filter 110B can have larger filter pores at the top of thefilter and progressively smaller filters pores toward the bottom of thefilter. In another embodiment, the first filter 110A or the secondfilter 110B can have filter pores of a similar pore size throughout theentire filter. In these embodiments, the first filter surface 126A orthe second filter surface 126B can be a surface of the pores. In anotherembodiment, the first filter 110A or the second filter 110B can be amesh or matrix structure and the first filter surface 126A or the secondfilter surface 126B can be a mesh or matrix surface.

The first filter 110A or the second filter 110B can be a high-capacityfilter. Although not shown in FIG. 11A, it is contemplated by thisdisclosure that the first filter 110A or the second filter 110B canrefer to a plurality of filters in a stacked arrangement.

The first filter 110A can comprise, hold, or carry the infectious agent102 when a fluid sample 124 comprising or carrying the infectious agent102 is introduced to the first filter 110A. For example, the fluidsample 124 can be introduced to the first filter 110A when the fluidsample 124 is poured over or injected through the first filter 110A. Thesecond filter 110B can also comprise, hold, or carry the infectiousagent 102 when a fluid sample 124 comprising or carrying the infectiousagent 102 is introduced to the second filter 110B. For example, thefluid sample 124 can be introduced to the second filter 110B when thefluid sample 124 is poured over or injected through the second filter110B. The first filter 110A or the second filter 110B can isolate orseparate the infectious agent 102 or other molecules or cells from thesupernatant of the fluid sample 124.

In one embodiment, the first filter 110A or the first filter surface126A and the second filter 110B or the second filter surface 126B cancomprise the anti-infective 104. For example, the first filter 110A orthe second filter 110B can comprise the anti-infective 104 when thefirst filter surface 126A or the second filter surface 126B is coatedwith the anti-infective 104 or exposed to the anti-infective 104 beforeintroducing the fluid sample 124 to the first filter 110A or the secondfilter 110B. In an alternative embodiment, the anti-infective 104 can beadded or introduced to the first filter 110A or the second filter 110Bafter exposing the first filter 110A or the second filter 110B to thefluid sample 124.

In yet another embodiment, the anti-infective 104 can be introducedthrough an additional solution exposed to the first filter 110A, thesecond filter 110B, or a combination thereof. For example, theanti-infective 104 can be introduced through a nutrient solution 130.

The anti-infective 104 can comprise a bacteriostatic anti-infective, abactericidal anti-infective, an anti-fungal anti-infective, an antiviralanti-infective, a prion inhibitor, or a combination thereof. In anotherembodiment, the anti-infective 104 can be a bacterial growth inhibitoror stimulator. The bacterial growth inhibitor or stimulator canselectively inhibit or promote the growth of gram positive or gramnegative bacteria. The bacterial growth inhibitor or stimulator cancomprise a dye or a chemical compound. In some embodiments, the dye caninclude, but is not limited to, Methylene blue, Bromothymol blue, EosinB, Safranin O, Crystal violet, or a combination thereof. The chemicalcompound can include, but is not limited to, sodium azide, bile acids,high sodium chloride, or a combination thereof. The anti-infective 104can also comprise a carbon source other than glucose, such as lactose ormannose, to select for certain bacterial species. A bacterial growthinhibitor or stimulant such as urea, citrate, or certain amino acids canalso be introduced to the first filter 110A, the second filter 110B, ora combination thereof.

The first filter housing 108A or the second filter housing 108B can haveat least one opening which allows fluid or supernatant from the fluidsample 124 to evacuate the first filter housing 108A or the secondfilter housing 108B. For example, step 11A can include the additionalstep of discarding the fluid or supernatant from the fluid sample 124through the opening after isolating the infectious agent 102 on thefirst filter surface 126A or the second filter surface 126B.

In an alternative embodiment not shown in FIG. 11A, a stimulus solutioncan be added to the fluid sample 124 before introducing the fluid sample124 to the first filter 110A or the second filter 110B. The stimulussolution can be a nutrient or growth solution. The stimulus solution canhave a different composition than the nutrient solution 130. Thestimulus solution can be a super nutrient solution.

The fluid sample 124 can also be pre-filtered in a step before step 11A.This pre-filtering step can involve filtering the fluid sample 124 usinga filter, a microfluidic filter, or a combination thereof to filter outother larger cellular components including blood cells or epithelialcells from the fluid sample 124 when the fluid sample 124 is composed ofbodily fluid.

The same fluid delivery device 106 or another fluid delivery device 106can also be used to deliver or inject nutrient solution 130 to the firstfilter housing 108A, the second filter housing 108B, or a combinationthereof in step 11B. The fluid delivery device 106 can continuously orperiodically expose the first filter surface 126A, the second filtersurface 126B, or a combination thereof to the nutrient solution 130.

After exposing the first filter 110A or the second filter 110B to thenutrient solution 130, another fluid delivery device 106 or the samefluid delivery device 106 can be used to deliver or inject a knownconcentration of glucose 502 to the first filter housing 108A or thefirst filter 110A, the second filter housing 108B or the second filter110B, or a combination thereof in an optional step 11C.

The first filter 110A, the second filter 110B, or a combination thereofcan be heated to a temperature of between 30° C. and 40° C. and allowedto incubate for an incubation period 132 in step 11D. In one embodiment,the first filter 110A or the second filter 110B can be incubated whilein the first filter housing 108A or the second filter housing 108B,respectively. In another embodiment, the first filter 110A or the secondfilter 110B can be removed from the first filter housing 108A or thesecond filter housing 108B, respectively, prior to incubation. In someembodiments, the first filter 110A, the second filter 110B, or acombination thereof can be incubated with the nutrient solution 130 andthe known concentration of glucose 502. In other embodiments, the firstfilter 110A, the second filter 110B, or a combination thereof can beincubated with the nutrient solution 130.

In some embodiments, the incubation period 132 can range from 15 minutesto over one hour. In other embodiments, the incubation period 132 can beless than 15 minutes. When glucose 502 is added to the system 1100, theincubation period 132 can range from one hour to five hours. In otherembodiments involving exogenous glucose 502, the incubation period 132can exceed five hours. The incubation period 132 can be adjusted basedon the type of infectious agent 102, such as the type of bacteria,fungus, virus, or prion suspected in the fluid sample 124.

The incubation period 132 can also be adjusted based on the suspectedamount of the infectious agent 102 present in the fluid sample 124, theamount or volume of the fluid sample 124, the amount of glucose 502added, or a combination thereof. For example, the incubation period 132can be increased when the amount of the infectious agent 102 is below athreshold amount. The first filter 110A or the second filter 110B can beallowed to incubate with the nutrient solution 130 in order to promotethe proliferation of the infectious agent 102 on the first filtersurface 126A or the second filter surface 126B.

One advantage of incubating the first filter 110A and the second filter110B is to increase the sensitivity of the system 1100 to small amountsof the infectious agent 102. For example, incubating the first filter110A and the second filter 110B can allow the system 1100 to reduce itslevel of detection.

After incubating the first filter 110A or the second filter 110B, theeffluent or outflow of the nutrient solution 130 and/or the solution ofglucose 502 exposed to the first filter 110A or the second filter 110Bcan be sampled. The effluent or outflow of the nutrient solution 130and/or the solution of glucose 502 exposed to the first filter 110A canbe referred to as the first sample effluent 1102A. The effluent oroutflow of the nutrient solution 130 and/or the solution of glucose 502exposed to the second filter 110B can be referred to as the secondsample effluent 1102B. The first sample effluent 1102A can be the sampleeffluent 134A depicted in FIGS. 1 and 8 when glucose 502 is not added tothe system 1100 or the sample effluent 504 depicted in FIG. 5 whenglucose 502 is added to the system 110. The second sample effluent 1102Bcan be the sample effluent 134 depicted in FIGS. 1 and 8 when glucose502 is not added to the system 1100 or the sample effluent 504 depictedin FIG. 5 when glucose 502 is added to the system 110.

The steps depicted in FIG. 11A do not require the particular order shownto achieve the desired result and certain steps or processes may occurin parallel.

FIG. 11B illustrates a variation of the system 1100 of FIG. 11A usingelectrochemical sensors. As depicted in FIG. 11B, the system 1100 ofFIG. 11A can further comprise a first sensing device 116A, a secondsensing device 116B, or a combination thereof. Any of the first sensingdevice 116A or the second sensing device 116B can be the sensing device116 of FIG. 1, 2A, 2B, 3A, or 3B. For example, any of the first sensingdevice 116A or the second sensing device 116B can be the electrochemicalcell shown in FIG. 2A, 2B, 3A, or 3B.

The first sample effluent 1102A can be analyzed by the first sensingdevice 116A and the second sample effluent 1102B can be analyzed by thesecond sensing device 116B in step 11E(a). As depicted in FIG. 11B, inone embodiment, the first sample effluent 1102A can be analyzed byinserting a portion of the first sensing device 116A directly into thefirst sample effluent 1102A and the second sample effluent 1102B can beanalyzed by inserting a portion of the second sensing device 116Bdirectly into the second sample effluent 1102B. In an alternativeembodiment not shown in FIG. 11B but contemplated by the disclosure, thefirst sample effluent 1102A can be analyzed by applying or introducingan aliquot of the first sample effluent 1102A to the first sensingdevice 116A and the second sample effluent 1102B can be analyzed byapplying or introducing an aliquot of the second sample effluent 1102Bto the second sensing device 116B.

In another embodiment shown in FIG. 11B, the same first sensing device116A can be used to analyze the first sample effluent 1102A and thesecond sample effluent 1102B in step 11E(b). In this embodiment, thefirst sensing device 116A can be cleaned or recalibrated after eachanalysis or use.

The first sample effluent 1102A and the second sample effluent 1102B caneach comprise a solution characteristic. The solution characteristic canrefer to one or more attributes of the solution making up the firstsample effluent 1102A, the second sample effluent 1102B, or acombination thereof. For example, the solution characteristic caninclude a concentration of a solute, analyte, or molecule, an absolutenumber or molecular count of solutes, analytes, or molecules insolution, a solution temperature, or a combination thereof. For example,the solution characteristic can refer to the amount or concentration ofions, organic molecules such as amino acids, vitamins or glucose,minerals, or other inorganic compounds in the first sample effluent1102A, the second sample effluent 1102B, or a combination thereof.

The solution characteristic can vary as a result of ions, molecules,minerals, or nutrients produced by, consumed by, or otherwise attributedto the infectious agent 102 on the first filter surface 126A, the secondfilter surface 126B, or a combination thereof. In one embodiment, thefirst sample effluent 1102A, the second sample effluent 1102B, or acombination thereof can comprise hydrogen ions (H⁺) as a byproduct ofbacterial cell metabolism or growth. In this embodiment, theconcentration or amount of hydrogen ions ((H⁺) can change over time inone sample effluent (e.g., in the first sample effluent 1102A) or differbetween the first sample effluent 1102A and the second sample effluent1102B based on the presence, proliferation, or activity of theinfectious agent 102 exposed to the first sample effluent 1102A, thesecond sample effluent 1102B, or a combination thereof.

In other embodiments, the first sample effluent 1102A, the second sampleeffluent 1102B, or a combination thereof can comprise differing orchanging concentrations or amounts of adenosine triphosphate (ATP),carbon dioxide (CO₂), lactic acid, carbonic acid, nitrates (NO₃ ⁻), or acombination thereof attributed to the infectious agent 102.

A change in the solution characteristic can cause a change in theelectrical characteristic of the first sensing device 116A, the secondsensing device 116B, or a combination thereof. A parameter analyzer 114can monitor the electrical characteristic of the first sensing device116A, the second sensing device 116B, or a combination thereof.

As depicted in FIG. 11B, the parameter analyzer 114 can be integratedinto one device with the first sensing device 116A, the second sensingdevice 116B, or a combination thereof. For example, the parameteranalyzer 114 can be fabricated on the same substrate as the firstsensing device 116A, the second sensing device 116B, or a combinationthereof. In other embodiments not shown in FIG. 11B, the parameteranalyzer 114 can be a standalone unit or device coupled to the firstsensing device 116A, the second sensing device 116B, or a combinationthereof.

The parameter analyzer 114 can monitor a first electrical characteristicof the first sensing device 116A exposed to the first sample effluent1102A. Another parameter analyzer 114 or the same parameter analyzer 114can monitor a second electrical characteristic of the second sensingdevice 116B exposed to the second sample effluent 1102B.

The electrical characteristic, including the first electricalcharacteristic and the second electrical characteristic, can include,but is not limited to, a voltage, a current, an impedance, a resistance,a capacitance, a resonant frequency, a noise level, a level ofinduction, or a combination thereof measured at or near the firstsensing device 116A, the second sensing device 116B, or a combinationthereof. The change in the electrical characteristic can include, but isnot limited to, a voltage change, an impedance change, a current change,a capacitance change, a resistance change, a change in resonantfrequency, a noise level change, an induction change, or a combinationthereof measured at or near the first sensing device 116A, the secondsensing device 116B, or a combination thereof.

In one embodiment, the parameter analyzer 114 can be a voltage meter. Inother embodiments, the parameter analyzer 114 can be, but is not limitedto, a multimeter, an ammeter, a capacitance analyzer, or a combinationthereof.

For example, monitoring the first electrical characteristic can involvedetermining a first voltage change at a first functionalization layer(such as the functionalization layer 208 in FIG. 2A, 2B, 3A, or 3B) ofthe first sensing device 116A exposed to the first sample effluent1102A. The first voltage change can be with respect to a voltage at afirst reference electrode (such as either the external referenceelectrode 202 of FIGS. 2A and 3A or the on-chip reference electrode ofFIGS. 2B and 3B) of the first sensing device 116A exposed to the firstsample effluent 1102A. In these example embodiments, the firstfunctionalization layer can cover the working electrode depicted in FIG.2A or 3A or cover the working electrode 214 of the first sensing device116A.

Also, for example, monitoring the second electrical characteristic caninvolve determining a second voltage change at a secondfunctionalization layer (such as the functionalization layer 208 in FIG.2A, 2B, 3A, or 3B) of the second sensing device 116B exposed to thesecond sample effluent 1102B. The second voltage change can be withrespect to a voltage at a second reference electrode (such as either theexternal reference electrode 202 of FIGS. 2A and 3A or the on-chipreference electrode of FIGS. 2B and 3B) of the second sensing device116B exposed to the second sample effluent 1102B. In these exampleembodiments, the second functionalization layer can cover the workingelectrode of the second sensing device 116B.

When only one sensing device (such as the first sensing device 116A) isused to sample the sample effluents, the parameter analyzer 114 canmonitor the electrical characteristic of the first sensing device 116Aexposed to the first sample effluent 1102A and the electricalcharacteristic of the same first sensing device 116A exposed to thesecond sample effluent 1102B. In this embodiment, the electricalcharacteristic of the first sensing device 116A while sampling the firstsample effluent 1102A can be referred to as the first electricalcharacteristic and the electrical characteristic of the first sensingdevice 116A while sampling the second sample effluent 1102B can bereferred to as the second electrical characteristic.

The parameter analyzer 114 can compare the first electricalcharacteristic, including a change in the first electricalcharacteristic, with the second electrical characteristic, including achange in the second electrical characteristic, to assess thesusceptibility of the infectious agent 102 to the anti-infective 104. Insome embodiments, the first electrical characteristic can differ fromthe second electrical characteristic when the solution characteristic ofthe first sample effluent 1102A differs from the solution characteristicof the second sample effluent 1102B as a result of differences in theconcentration or amount of ions, analytes, molecules, minerals, or othersolutes present in the sample effluents.

For example, the first electrical characteristic and the secondelectrical characteristic can differ when the solution characteristic ofthe first sample effluent 1102A and the solution characteristic of thesecond sample effluent differ in their pH. In other embodiments, thefirst electrical characteristic can differ from the second electricalcharacteristic when the solution characteristic of the first sampleeffluent 1102A differs from the solution characteristic of the secondsample effluent 1102B as a result of differences in the temperature ofthe solution.

In one embodiment, the parameter analyzer 114 can assess thesusceptibility of the infectious agent 102 to the anti-infective 104 asa binary assessment or a tiered assessment. In another embodiment, areader or computing device connected or communicatively coupled to theparameter analyzer 114 can assess the susceptibility of the infectiousagent 102 to the anti-infective 104 as a binary assessment or a tieredassessment.

The parameter analyzer 114 or the reader communicatively coupled to theparameter analyzer 114 can assess the susceptibility of the infectiousagent 102 as either resistant or non-resistant to the anti-infective104. In this embodiment, the second filter 110B or the second filtersurface 126B can comprise a set amount of the anti-infective 104. Theparameter analyzer 114 or a reader communicatively coupled to theparameter analyzer 114 can then assess the susceptibility of theinfectious agent 102 as either resistant or non-resistant based on anydetected differences in the first electrical characteristic and thesecond electrical characteristic or any detected differences in thechange in the first electrical characteristic and the change in thesecond electrical characteristic.

The parameter analyzer 114 or the reader communicatively coupled to theparameter analyzer 114 can assess the susceptibility of the infectiousagent 102 as not resistant to the anti-infective 104 when the parameteranalyzer 114 or the reader fails to detect a difference or astatistically significant difference between the first electricalcharacteristic and the second electrical characteristic or astatistically significant difference between the change in the firstelectrical characteristic and the change in the second electricalcharacteristic. More specifically, a statistically significantdifference in the electrical characteristic can be a differenceexceeding a threshold value.

In other embodiments, the parameter analyzer 114 or the readercommunicatively coupled to the parameter analyzer 114 can assess thelevel of susceptibility of the infectious agent 102 on a tiered scale.For example, the parameter analyzer 114 or the reader communicativelycoupled to the parameter analyzer 114 can assess the susceptibility ofthe infectious agent 102 as being resistant, mildly susceptible, orsusceptible to the anti-infective 104. In these embodiments, additionalfilter surfaces, including a third filter surface, can be used whichcomprise anti-infectives 104 of different concentrations. While threecategories of susceptibility are discussed, it should be understood byone of ordinary skill in the art that four or greater categories ofsusceptibility or four or more filters can be used to assess the levelof susceptibility of the infectious agent 102 to differingconcentrations of the anti-infective 104.

The parameter analyzer 114 can also have or be connected to a display113 or display component configured to provide a result of the detectionor a read-out of the electrical characteristic of the first sensingdevice 116A, the second sensing device 116B, or a combination thereof.In some embodiments, the parameter analyzer 114 can be a mobile device,a handheld device, a tablet device, or a computing device such as alaptop or desktop computer and the display 113 can be a mobile devicedisplay, a handheld device display, a tablet display, or a laptop ordesktop monitor.

In one embodiment, the parameter analyzer 114 can display a resultindicating the level of susceptibility of the infectious agent 102 inthe fluid sample 124 via the display 113. In another embodiment, theparameter analyzer 114 can wirelessly communicate a result indicatingthe presence of an infectious agent 102 in the fluid sample 124 to acomputing device having the display 113.

FIG. 11C illustrates a variation of the system of FIG. 11A using glucosesensors. As depicted in FIG. 11C, the system 1100 of FIG. 11A canfurther comprise a first sensing device 500A, a second sensing device500B, or a combination thereof. Any of the first sensing device 500A orthe second sensing device 500B can be the sensing device 500 of FIG. 5.For example, any of the first sensing device 500A or the second sensingdevice 500B can be the glucose sensor shown in FIG. 5.

The first sample effluent 1102A can be analyzed by the first sensingdevice 500A and the second sample effluent 1102B can be analyzed by thesecond sensing device 500B in step 11E(c). As depicted in FIG. 11C, inone embodiment, the first sample effluent 1102A can be analyzed byinserting a portion of the first sensing device 500A directly into thefirst sample effluent 1102A and the second sample effluent 1102B can beanalyzed by inserting a portion of the second sensing device 500Bdirectly into the second sample effluent 1102B. In an alternativeembodiment not shown in FIG. 11C but contemplated by the disclosure, thefirst sample effluent 1102A can be analyzed by applying or introducingan aliquot of the first sample effluent 1102A to the first sensingdevice 500A and the second sample effluent 1102B can be analyzed byapplying or introducing an aliquot of the second sample effluent 1102Bto the second sensing device 500B.

In another embodiment shown in FIG. 11C, the same first sensing device500A can be used to analyze the first sample effluent 1102A and thesecond sample effluent 1102B in step 11E(d). In this embodiment, thefirst sensing device 500A can be cleaned or recalibrated after eachanalysis or use.

The first sample effluent 1102A and the second sample effluent 1102B caneach comprise a solution characteristic. The solution characteristic canrefer to one or more attributes of the solution making up the firstsample effluent 1102A, the second sample effluent 1102B, or acombination thereof. For example, the solution characteristic caninclude a concentration of a solute, analyte, or molecule, an absolutenumber or molecular count of solutes, analytes, or molecules insolution, a solution temperature, or a combination thereof. For example,the solution characteristic can refer to the amount or concentration ofions, organic molecules such as amino acids, vitamins or glucose,minerals, or other inorganic compounds in the first sample effluent1102A, the second sample effluent 1102B, or a combination thereof.

The solution characteristic can vary as a result of nutrients consumedby the infectious agent 102 on the first filter surface 126A, the secondfilter surface 126B, or a combination thereof. For example, as depictedin step 11C, a known concentration of glucose 502 can be added to thefirst filter housing 108A, the first filter 110A, the second filterhousing 108B, the second filter 110B, or a combination thereof.

After the incubation period 132, the concentration of glucose 502 in thefirst sample effluent 1102A can differ from the concentration of glucose502 in the second sample effluent 1102B based on the presence,proliferation, or activity of the infectious agent 102 on the firstfilter surface 126A, the second filter surface 126B, or a combinationthereof.

A change in the glucose concentration can cause a change in theelectrical characteristic of the first sensing device 500A, the secondsensing device 500B, or a combination thereof. A parameter analyzer 114can monitor the electrical characteristic of the first sensing device500A, the second sensing device 500B, or a combination thereof.

As depicted in FIG. 11C, the parameter analyzer 114 can be integratedinto one device with the first sensing device 500A, the second sensingdevice 500B, or a combination thereof. For example, the parameteranalyzer 114 can be fabricated on the same substrate as the firstsensing device 500A, the second sensing device 500B, or a combinationthereof. In other embodiments not shown in FIG. 11C, the parameteranalyzer 114 can be a standalone unit or device coupled to the firstsensing device 500A, the second sensing device 500B, or a combinationthereof.

The parameter analyzer 114 can monitor a first electrical characteristicof the first sensing device 500A exposed to the first sample effluent1102A. Another parameter analyzer 114 or the same parameter analyzer 114can monitor a second electrical characteristic of the second sensingdevice 500B exposed to the second sample effluent 1102B.

The electrical characteristic, including the first electricalcharacteristic and the second electrical characteristic, can include,but is not limited to, a voltage, a current, an impedance, a resistance,a capacitance, a resonant frequency, a noise level, a level ofinduction, or a combination thereof measured at or near the firstsensing device 500A, the second sensing device 500B, or a combinationthereof. The change in the electrical characteristic can include, but isnot limited to, a voltage change, an impedance change, a current change,a capacitance change, a resistance change, a change in resonantfrequency, a noise level change, an induction change, or a combinationthereof measured at or near the first sensing device 500A, the secondsensing device 500B, or a combination thereof.

In one embodiment, the parameter analyzer 114 can include a voltagemeter and an ammeter. In other embodiments, the parameter analyzer 114can be, but is not limited to, a multimeter, a singular voltage meter, asingular ammeter, a capacitance analyzer, or a combination thereof.

When only one sensing device (such as the first sensing device 500A) isused to sample the sample effluents, the parameter analyzer 114 canmonitor the electrical characteristic of the first sensing device 500Aexposed to the first sample effluent 1102A and the electricalcharacteristic of the same first sensing device 500A exposed to thesecond sample effluent 1102B. In this embodiment, the electricalcharacteristic of the first sensing device 500A while sampling the firstsample effluent 1102A can be referred to as the first electricalcharacteristic and the electrical characteristic of the first sensingdevice 500A while sampling the second sample effluent 1102B can bereferred to as the second electrical characteristic.

The parameter analyzer 114 can compare the first electricalcharacteristic, including a change in the first electricalcharacteristic, with the second electrical characteristic, including achange in the second electrical characteristic, to assess thesusceptibility of the infectious agent 102 to the anti-infective 104. Insome embodiments, the first electrical characteristic can differ fromthe second electrical characteristic when the solution characteristic ofthe first sample effluent 1102A differs from the solution characteristicof the second sample effluent 1102B as a result of differences in theconcentration or amount of a nutrient added to the system 1100. Forexample, the first electrical characteristic and the second electricalcharacteristic can differ when the glucose concentration of the firstsample effluent 1102A and the glucose concentration of the second sampleeffluent differ.

In one embodiment, the parameter analyzer 114 can assess thesusceptibility of the infectious agent 102 to the anti-infective 104 asa binary assessment or a tiered assessment. In another embodiment, areader or computing device connected or communicatively coupled to theparameter analyzer 114 can assess the susceptibility of the infectiousagent 102 to the anti-infective 104 as a binary assessment or a tieredassessment.

The parameter analyzer 114 or the reader communicatively coupled to theparameter analyzer 114 can assess the susceptibility of the infectiousagent 102 as either resistant or non-resistant to the anti-infective104. In this embodiment, the second filter 110B or the second filtersurface 126B can comprise a set amount of the anti-infective 104. Theparameter analyzer 114 or a reader communicatively coupled to theparameter analyzer 114 can then assess the susceptibility of theinfectious agent 102 as either resistant or non-resistant based on anydetected differences in the first electrical characteristic and thesecond electrical characteristic or any detected differences in thechange in the first electrical characteristic and the change in thesecond electrical characteristic.

The parameter analyzer 114 or the reader communicatively coupled to theparameter analyzer 114 can assess the susceptibility of the infectiousagent 102 as not resistant to the anti-infective 104 when the parameteranalyzer 114 or the reader fails to detect a difference or astatistically significant difference between the first electricalcharacteristic and the second electrical characteristic or astatistically significant difference between the change in the firstelectrical characteristic and the change in the second electricalcharacteristic. More specifically, a statistically significantdifference in the electrical characteristic can be a differenceexceeding a threshold value.

In other embodiments, the parameter analyzer 114 or the readercommunicatively coupled to the parameter analyzer 114 can assess thelevel of susceptibility of the infectious agent 102 on a tiered scale.For example, the parameter analyzer 114 or the reader communicativelycoupled to the parameter analyzer 114 can assess the susceptibility ofthe infectious agent 102 as being resistant, mildly susceptible, orsusceptible to the anti-infective 104. In these embodiments, additionalfilter surfaces, including a third filter surface, can be used whichcomprise anti-infectives 104 of different concentrations. While threecategories of susceptibility are discussed, it should be understood byone of ordinary skill in the art that four or greater categories ofsusceptibility or four or more filters can be used to assess the levelof susceptibility of the infectious agent 102 to differingconcentrations of the anti-infective 104.

The parameter analyzer 114 can also have or be connected to a display113 or display component configured to provide a result of the detectionor a read-out of the electrical characteristic of the first sensingdevice 500A, the second sensing device 500B, or a combination thereof.In some embodiments, the parameter analyzer 114 can be a mobile device,a handheld device, a tablet device, or a computing device such as alaptop or desktop computer and the display 113 can be a mobile devicedisplay, a handheld device display, a tablet display, or a laptop ordesktop monitor.

In one embodiment, the parameter analyzer 114 can display a resultindicating the level of susceptibility of the infectious agent 102 inthe fluid sample 124 via the display 113. In another embodiment, theparameter analyzer 114 can wirelessly communicate a result indicatingthe presence of an infectious agent 102 in the fluid sample 124 to acomputing device having the display 113.

FIG. 11D illustrates a variation of the system of FIG. 11A usinglight-addressable potentiometric (LAP) sensors. As depicted in FIG. 11D,the system 1100 of FIG. 11A can further comprise a first sensing device800A, a second sensing device 800B, or a combination thereof. Any of thefirst sensing device 800A or the second sensing device 800B can be thesensing device 800 of FIG. 8. For example, any of the first sensingdevice 800A or the second sensing device 800B can be the photocurrent orLAP sensor shown in FIG. 8.

The first sample effluent 1102A can be analyzed by the first sensingdevice 800A and the second sample effluent 1102B can be analyzed by thesecond sensing device 800B in step 11E(e). As depicted in FIG. 11D, inone embodiment, the first sample effluent 1102A can be analyzed byinserting a portion of the first sensing device 800A directly into thefirst sample effluent 1102A and the second sample effluent 1102B can beanalyzed by inserting a portion of the second sensing device 800Bdirectly into the second sample effluent 1102B. In an alternativeembodiment not shown in FIG. 11C but contemplated by the disclosure, thefirst sample effluent 1102A can be analyzed by applying or introducingan aliquot of the first sample effluent 1102A to the first sensingdevice 800A and the second sample effluent 1102B can be analyzed byapplying or introducing an aliquot of the second sample effluent 1102Bto the second sensing device 800B.

In another embodiment shown in FIG. 11D, the same first sensing device800A can be used to analyze the first sample effluent 1102A and thesecond sample effluent 1102B in step 11E(f). In this embodiment, thefirst sensing device 800A can be cleaned or recalibrated after eachanalysis or use.

The first sample effluent 1102A and the second sample effluent 1102B caneach comprise a solution characteristic. The solution characteristic canrefer to one or more attributes of the solution making up the firstsample effluent 1102A, the second sample effluent 1102B, or acombination thereof. For example, the solution characteristic caninclude a concentration of a solute, analyte, or molecule, an absolutenumber or molecular count of solutes, analytes, or molecules insolution, a solution temperature, or a combination thereof. For example,the solution characteristic can refer to the amount or concentration ofions, organic molecules such as amino acids, vitamins or glucose,minerals, or other inorganic compounds in the first sample effluent1102A, the second sample effluent 1102B, or a combination thereof.

The solution characteristic can vary as a result of ions, molecules,minerals, or nutrients produced by, consumed by, or otherwise attributedto the infectious agent 102 on the first filter surface 126A, the secondfilter surface 126B, or a combination thereof. In one embodiment, thefirst sample effluent 1102A, the second sample effluent 1102B, or acombination thereof can comprise hydrogen ions (H⁺) as a byproduct ofbacterial cell metabolism or growth. In this embodiment, theconcentration or amount of hydrogen ions ((H⁺) can change over time inone sample effluent (e.g., in the first sample effluent 1102A) or differbetween the first sample effluent 1102A and the second sample effluent1102B based on the presence, proliferation, or activity of theinfectious agent 102 exposed to the first sample effluent 1102A, thesecond sample effluent 1102B, or a combination thereof.

In other embodiments, the first sample effluent 1102A, the second sampleeffluent 1102B, or a combination thereof can comprise differing orchanging concentrations or amounts of adenosine triphosphate (ATP),carbon dioxide (CO₂), lactic acid, carbonic acid, nitrates (NO₃ ⁻), or acombination thereof attributed to the infectious agent 102.

A change in the solution characteristic can cause a change in theelectrical characteristic of the first sensing device 800A, the secondsensing device 800B, or a combination thereof. A parameter analyzer 114can monitor the electrical characteristic of the first sensing device800A, the second sensing device 800B, or a combination thereof. In oneembodiment, the parameter analyzer 114 can include voltage source 908and the ammeter 910 of FIG. 9. In other embodiments, the parameteranalyzer 114 can include a voltmeter, a multimeter, a capacitanceanalyzer, or a combination thereof.

As depicted in FIG. 11D, the parameter analyzer 114 can be integratedinto one device with the first sensing device 800A, the second sensingdevice 800B, or a combination thereof. For example, the parameteranalyzer 114 can be fabricated on the same substrate as the firstsensing device 800A, the second sensing device 800B, or a combinationthereof. In other embodiments not shown in FIG. 11D, the parameteranalyzer 114 can be a standalone unit or device coupled to the firstsensing device 800A, the second sensing device 800B, or a combinationthereof.

The parameter analyzer 114 can monitor a first electrical characteristicof the first sensing device 800A exposed to the first sample effluent1102A. Another parameter analyzer 114 or the same parameter analyzer 114can monitor a second electrical characteristic of the second sensingdevice 800B exposed to the second sample effluent 1102B.

The electrical characteristic, including the first electricalcharacteristic and the second electrical characteristic, can include,but is not limited to, a voltage, a current, an impedance, a resistance,a capacitance, a resonant frequency, a noise level, a level ofinduction, or a combination thereof measured at or near the firstsensing device 800A, the second sensing device 800B, or a combinationthereof. The change in the electrical characteristic can include, but isnot limited to, a voltage change, an impedance change, a current change,a capacitance change, a resistance change, a change in resonantfrequency, a noise level change, an induction change, or a combinationthereof measured at or near the first sensing device 800A, the secondsensing device 800B, or a combination thereof.

As depicted in FIG. 11D, a light source 804 can direct light 802 ofspecific wavelengths at the doped semiconductor layer 906 (see FIG. 9)of the first sensing device 800A, the second sensing device 800B, or acombination thereof. When the semiconducting material, such as silicon,in the semiconductor layer 906 absorbs light 802 matching its excitationfrequency, electron-hole pairs are generated in the bulk of thesemiconductor layer 906 and electrons move to the interface between thesemiconductor layer 906 and the insulator layer 904. As a result, atransient photocurrent can be detected by the parameter analyzer 114.The light source 804 can modulate the wavelengths of the light 802directed at the semiconductor layer 906 in order to induce analternating current (AC) photocurrent.

The parameter analyzer 114 can also apply a bias voltage to the firstsample effluent 1102A, the second sample effluent 1102B, or acombination thereof via an external reference electrode (such as theexternal reference electrode 900 of FIG. 9). The bias voltage can be setso as to repel electrons from the doped semiconductor layer of the firstsensing device 800A, the second sensing device 800B, or a combinationthereof to form a depletion layer. The bias voltage can be set so as torepel the electrons moving to the interface between the semiconductorlayer and the insulator layer due to the light 802 directed at thesemiconductor layer. At a low enough bias voltage, the depletion layeris not formed. At a large enough bias voltage, the photocurrentincreases until reaching a limiting value.

A change in the solution characteristic of the first sample effluent1102A, the second sample effluent 1102B, or a combination thereof (suchas a change in analyte concentration or pH change) can change the biasvoltage needed to maintain the constant photocurrent detected by theparameter analyzer 114.

When only one sensing device (such as the first sensing device 800A) isused to sample the sample effluents, the parameter analyzer 114 canmonitor the electrical characteristic of the first sensing device 800Aexposed to the first sample effluent 1102A and the electricalcharacteristic of the same first sensing device 800A exposed to thesecond sample effluent 1102B. In this embodiment, the electricalcharacteristic of the first sensing device 800A while sampling the firstsample effluent 1102A can be referred to as the first electricalcharacteristic and the electrical characteristic of the first sensingdevice 800A while sampling the second sample effluent 1102B can bereferred to as the second electrical characteristic.

The parameter analyzer 114 can compare the first electricalcharacteristic (such as the bias voltage applied to the first sensingdevice 800A), including a change in the first electrical characteristic(such as a change in the bias voltage needed to maintain a constantphotocurrent at the first sensing device 800A), with the secondelectrical characteristic (such as the bias voltage applied to thesecond sensing device 800B), including a change in the second electricalcharacteristic (such as a change in the bias voltage needed to maintaina constant photocurrent at the second sensing device 800B), to assessthe susceptibility of the infectious agent 102 to the anti-infective104. In some embodiments, the first electrical characteristic can differfrom the second electrical characteristic when the solutioncharacteristic of the first sample effluent 1102A differs from thesolution characteristic of the second sample effluent 1102B as a resultof differences in the concentration or amount of ions, analytes,molecules, minerals, or other solutes present in the sample effluents.For example, the first electrical characteristic and the secondelectrical characteristic can differ when the solution characteristic ofthe first sample effluent 1102A and the solution characteristic of thesecond sample effluent differ in their pH.

In one embodiment, the parameter analyzer 114 can assess thesusceptibility of the infectious agent 102 to the anti-infective 104 asa binary assessment or a tiered assessment. In another embodiment, areader or computing device connected or communicatively coupled to theparameter analyzer 114 can assess the susceptibility of the infectiousagent 102 to the anti-infective 104 as a binary assessment or a tieredassessment.

The parameter analyzer 114 or the reader communicatively coupled to theparameter analyzer 114 can assess the susceptibility of the infectiousagent 102 as either resistant or non-resistant to the anti-infective104. In this embodiment, the second filter 110B or the second filtersurface 126B can comprise a set amount of the anti-infective 104. Theparameter analyzer 114 or a reader communicatively coupled to theparameter analyzer 114 can then assess the susceptibility of theinfectious agent 102 as either resistant or non-resistant based on anydetected differences in the first electrical characteristic and thesecond electrical characteristic or any detected differences in thechange in the first electrical characteristic and the change in thesecond electrical characteristic.

The parameter analyzer 114 or the reader communicatively coupled to theparameter analyzer 114 can assess the susceptibility of the infectiousagent 102 as not resistant to the anti-infective 104 when the parameteranalyzer 114 or the reader fails to detect a difference or astatistically significant difference between the first electricalcharacteristic and the second electrical characteristic or astatistically significant difference between the change in the firstelectrical characteristic and the change in the second electricalcharacteristic. More specifically, a statistically significantdifference in the electrical characteristic can be a differenceexceeding a threshold value.

In other embodiments, the parameter analyzer 114 or the readercommunicatively coupled to the parameter analyzer 114 can assess thelevel of susceptibility of the infectious agent 102 on a tiered scale.For example, the parameter analyzer 114 or the reader communicativelycoupled to the parameter analyzer 114 can assess the susceptibility ofthe infectious agent 102 as being resistant, mildly susceptible, orsusceptible to the anti-infective 104. In these embodiments, additionalfilter surfaces, including a third filter surface, can be used whichcomprise anti-infectives 104 of different concentrations. While threecategories of susceptibility are discussed, it should be understood byone of ordinary skill in the art that four or greater categories ofsusceptibility or four or more filters can be used to assess the levelof susceptibility of the infectious agent 102 to differingconcentrations of the anti-infective 104.

The parameter analyzer 114 can also have or be connected to a display113 or display component configured to provide a result of the detectionor a read-out of the electrical characteristic of the first sensingdevice 800A, the second sensing device 800B, or a combination thereof.In some embodiments, the parameter analyzer 114 can be a mobile device,a handheld device, a tablet device, or a computing device such as alaptop or desktop computer and the display 113 can be a mobile devicedisplay, a handheld device display, a tablet display, or a laptop ordesktop monitor.

In one embodiment, the parameter analyzer 114 can display a resultindicating the level of susceptibility of the infectious agent 102 inthe fluid sample 124 via the display 113. In another embodiment, theparameter analyzer 114 can wirelessly communicate a result indicatingthe presence of an infectious agent 102 in the fluid sample 124 to acomputing device having the display 113.

FIG. 12 illustrates a method 1200 of detecting an infectious agent 102in a fluid sample 124. The method 1200 can include introducing a fluidsample 124 to a surface, such as the filter surface 126, in a step 1202.The filter surface 126 can isolate, trap, or otherwise contain theinfectious agent 102 when a fluid sample 124 carrying or comprising theinfectious agent 102 is introduced to the filter surface 126. The method1200 can also include exposing the surface to a solution, such as thenutrient solution 130, in a step 1204. The method 1200 can furtherinclude sampling the solution after exposing the surface to the solutionin step 1206. Sampling the solution can include sampling the effluent oroutflow of the solution, such as the sample effluent 134. Sampling thesolution can also involve separating the solution from the surface sothe solution is not in fluid communication or contact with the surface,the infectious agent 102 on the surface, or a combination thereof whensampled.

The method 1200 can also include detecting a change in an electricalcharacteristic of a sensing device exposed to the solution sampledcorresponding to the presence of the infectious agent 102 in the fluidsample 124 in step 1208. When the sensing device is an electrochemicalcell such as the sensing device 116, detecting the change in theelectrical characteristic comprises determining a voltage change at afunctionalization layer covering a working electrode of theelectrochemical cell. The functionalization layer can be exposed to thesolution sampled and the voltage change can be determined with respectto a reference electrode, such as the external reference electrode 202of FIG. 2A or the on-chip reference electrode 216 of FIG. 2B, alsoexposed to the solution sampled.

FIG. 13 illustrates a method 1300 of detecting an infectious agent 102in a fluid sample 124. The method 1300 can include introducing a fluidsample 124 to a surface, such as the filter surface 126, in a step 1302.The filter surface 126 can isolate, trap, or otherwise contain theinfectious agent 102 when a fluid sample 124 carrying or comprising theinfectious agent 102 is introduced to the filter surface 126. The method1300 can also include exposing the surface to a solution, such as thenutrient solution 130, in step 1304.

The method 1300 can also include adding a known concentration of glucoseto the solution or the surface exposed to the solution in a step 1306.The method 1300 can further include incubating the solution or surfacewith the added glucose. The method 1300 can also include sampling thesolution comprising glucose in step 1308. Sampling the solution caninclude sampling the effluent or outflow of the solution comprisingglucose exposed to the surface, such as the sample effluent 504.Sampling the solution can also involve separating the solutioncomprising glucose from the surface so the solution comprising glucoseis not in fluid communication or contact with the surface, theinfectious agent 102 on the surface, or a combination thereof whensampled.

The method 1300 can also include detecting a change in an electricalcharacteristic of a sensing device exposed to the glucose solutionsampled corresponding to the presence of the infectious agent 102 in thefluid sample 124 in step 1310. When the sensing device is a glucosesensor, such as the sensing device 500, the change in the electricalcharacteristic is caused by a change in the glucose concentration of thesolution sampled.

FIG. 14 illustrates a method 1400 of detecting an infectious agent 102in a fluid sample 124. The method 1400 can include introducing a fluidsample 124 to a surface, such as the filter surface 126, in step 1402.The filter surface 126 can isolate, trap, or otherwise contain theinfectious agent 102 when a fluid sample 124 carrying or comprising theinfectious agent 102 is introduced to the filter surface 126. The method1400 can also include exposing the surface to a solution, such as thenutrient solution 130, in step 1404. The method 1400 can further includesampling the solution after exposing the surface to the solution in step1406. Sampling the solution can include sampling the effluent or outflowof the solution, such as the sample effluent 134. Sampling the solutioncan also involve separating the solution from the surface so thesolution is not in fluid communication or contact with the surface, theinfectious agent 102 on the surface, or a combination thereof whensampled.

The method 1400 can also include applying a bias voltage via a referenceelectrode to a sensing device, such as the sensing device 800, exposedto the solution sampled in step 1408. The method 1400 can also includedirecting light using a modulated light source at a semiconductor layer,such as the semiconductor layer 906 of FIG. 9, of the sensing device instep 1410. The method can also include detecting a photocurrent using anammeter coupled to the sensing device in step 1412. The method canfurther include determining a voltage change at a functionalizationlayer, such as the functionalization layer 902 of FIG. 9, covering aninsulator layer, such as the insulator layer 904, in contact with thesemiconductor layer of the sensing device. The voltage change, oranother change in the electrical characteristic, of the sensing deviceexposed to the solution sampled can correspond to the presence of aninfectious agent 102 in the fluid sample 124.

FIG. 15 illustrates a method 1500 for detecting a susceptibility of aninfectious agent 102 to an anti-infective 104. The method 1500 caninclude introducing a fluid sample 124 to a first surface, such as thefirst filter surface 126A, and a second surface, such as the secondfilter surface 126B, in a step 1502. The method 1500 can also includeexposing the first surface to a first solution, such as the nutrientsolution 130, in a step 1504. The first surface can comprise theinfectious agent 102 when the infectious agent 102 is present in thefluid sample 124.

The method 1500 can also include exposing the second surface to a secondsolution, such as additional instances of the nutrient solution 130 in astep 1506. The second surface can comprise an anti-infective 104. Thesecond surface can also comprise the infectious agent 102 when theinfectious agent 102 is present in the fluid sample 124.

The method 1500 can also include sampling the first solution afterexposing the first solution to the first surface in step 1508. Samplingthe first solution can include sampling the effluent or outflow of thefirst solution, such as the first sample effluent 1102A. In oneembodiment, sampling the first solution can also involve separating thefirst solution from the first surface so the first solution is not influid communication with the first surface, the infectious agent 102 onthe first surface, or a combination thereof when sampled. The method1500 can also include sampling the second solution after exposing thesecond solution to the second surface in step 1510. Sampling the secondsolution can include sampling the effluent or outflow of the secondsolution, such as the second sample effluent 1102B. In one embodiment,sampling the second solution can also involve separating the secondsolution from the second surface so the second solution is not in fluidcommunication with the second surface, the infectious agent 102 on thesecond surface, or a combination thereof when sampled.

The method 1500 can also include monitoring a first electricalcharacteristic of a first sensing device, such as the first sensingdevice 116A, the first sensing device 500A, or the first sensing device800A, exposed to the first solution sampled in step 1512. The method1500 can also include monitoring a second electrical characteristic of asecond sensing device, such as the second sensing device 116B, thesecond sensing device 500B, or the second sensing device 800B exposed tothe second solution sampled in step 1514. The method 1500 can furtherinclude comparing the first electrical characteristic and the secondelectrical characteristic to assess the susceptibility of the infectiousagent 102 to the anti-infective 104 in step 1516.

FIG. 16 illustrates another method 1600 for detecting a susceptibilityof an infectious agent 102 to an anti-infective 104. The method 1600 caninclude introducing a fluid sample 124 to a first surface, such as thefirst filter surface 126A, and a second surface, such as the secondfilter surface 126B, in a step 1602. The method 1600 can also includeexposing the first surface to a first solution, such as the nutrientsolution 130, in a step 1604. The first surface can comprise theinfectious agent 102 when the infectious agent 102 is present in thefluid sample 124.

The method 1600 can also include exposing the second surface to a secondsolution, such as additional instances of the nutrient solution 130 in astep 1606. The second surface can comprise an anti-infective 104. Thesecond surface can also comprise the infectious agent 102 when theinfectious agent 102 is present in the fluid sample 124.

The method 1600 can also include sampling the first solution afterexposing the first solution to the first surface in step 1608. Samplingthe first solution can include sampling the effluent or outflow of thefirst solution, such as the first sample effluent 1102A. In oneembodiment, sampling the first solution can also involve separating thefirst solution from the first surface so the first solution is not influid communication with the first surface, the infectious agent 102 onthe first surface, or a combination thereof. The method 1600 can alsoinclude sampling the second solution after exposing the second solutionto the second surface in step 1610. Sampling the second solution caninclude sampling the effluent or outflow of the second solution, such asthe second sample effluent 1102B. In one embodiment, sampling the secondsolution can also involve separating the second solution from the secondsurface so the second solution is not in fluid communication with thesecond surface, the infectious agent 102 on the second surface, or acombination thereof.

The method 1600 can also include monitoring a first electricalcharacteristic of a sensing device, such as the first sensing device116A, the first sensing device 500A, or the first sensing device 800A,exposed to the first solution sampled in step 1612. The method 1600 canalso include monitoring a second electrical characteristic of thesensing device exposed to the second solution sampled in step 1614. Themethod 1600 can further include comparing the first electricalcharacteristic and the second electrical characteristic to assess thesusceptibility of the infectious agent 102 to the anti-infective 104 instep 1616.

The flowcharts or process flows depicted in FIGS. 12-16 do not requirethe particular order shown to achieve the desired result and certainsteps or processes may occur in parallel.

Each of the individual variations or embodiments described andillustrated herein has discrete components and features which may bereadily separated from or combined with the features of any of the othervariations or embodiments. Modifications may be made to adapt aparticular situation, material, composition of matter, process, processact(s) or step(s) to the objective(s), spirit or scope of the presentinvention.

Methods recited herein may be carried out in any order of the recitedevents that is logically possible, as well as the recited order ofevents. For example, the flowcharts or process flows depicted in thefigures do not require the particular order shown to achieve the desiredresult. Moreover, additional steps or operations may be provided orsteps or operations may be eliminated to achieve the desired result.

It will be understood by one of ordinary skill in the art that all or aportion of the methods disclosed herein may be embodied in anon-transitory machine readable or accessible medium comprisinginstructions readable or executable by a processor or processing unit ofa computing device or other type of machine.

Furthermore, where a range of values is provided, every interveningvalue between the upper and lower limit of that range and any otherstated or intervening value in that stated range is encompassed withinthe invention. Also, any optional feature of the inventive variationsdescribed may be set forth and claimed independently, or in combinationwith any one or more of the features described herein.

All existing subject matter mentioned herein (e.g., publications,patents, patent applications and hardware) is incorporated by referenceherein in its entirety except insofar as the subject matter may conflictwith that of the present invention (in which case what is present hereinshall prevail). The referenced items are provided solely for theirdisclosure prior to the filing date of the present application. Nothingherein is to be construed as an admission that the present invention isnot entitled to antedate such material by virtue of prior invention.

Reference to a singular item, includes the possibility that there areplural of the same items present. More specifically, as used herein andin the appended claims, the singular forms “a,” “an,” “said” and “the”include plural referents unless the context clearly dictates otherwise.It is further noted that the claims may be drafted to exclude anyoptional element. As such, this statement is intended to serve asantecedent basis for use of such exclusive terminology as “solely,”“only” and the like in connection with the recitation of claim elements,or use of a “negative” limitation. Unless defined otherwise, alltechnical and scientific terms used herein have the same meaning ascommonly understood by one of ordinary skill in the art to which thisinvention belongs.

This disclosure is not intended to be limited to the scope of theparticular forms set forth, but is intended to cover alternatives,modifications, and equivalents of the variations or embodimentsdescribed herein. Further, the scope of the disclosure fully encompassesother variations or embodiments that may become obvious to those skilledin the art in view of this disclosure. The scope of the presentinvention is limited only by the appended claims.

What is claimed is:
 1. A system of assessing a susceptibility of aninfectious agent to an anti-infective, the system comprising: a fluiddelivery device configured to introduce a fluid sample to a firstsurface and a second surface; the same fluid delivery device or anotherfluid delivery device configured to introduce a first solution to thefirst surface comprising the infectious agent; the same fluid deliverydevice or another fluid delivery device configured to introduce a secondsolution to the second surface comprising the infectious agent, whereinat least one of the second surface and the second solution comprises ananti-infective; a first sensing device configured to be exposed to asample of the first solution after the first solution is exposed to thefirst surface, wherein a first electrical characteristic of the firstsensing device is monitored; a second sensing device configured to beexposed to a sample of the second solution after the second solution isexposed to the second surface, wherein a second electricalcharacteristic of the second sensing device is monitored; and aparameter analyzer configured to compare the first electricalcharacteristic, including a change in the first electricalcharacteristic, with the second electrical characteristic, including anychanges in the second electrical characteristic, wherein any differencesbetween the first electrical characteristic and the second electricalcharacteristic, or lack thereof, is used to assess the susceptibility ofthe infectious agent to the anti-infective.
 2. The system of claim 1,wherein the first sensing device is a first electrochemical cell andwherein the first electrical characteristic of the first sensing deviceis monitored by determining a first voltage change at a firstfunctionalization layer exposed to the first solution sampled, whereinthe first voltage change is with respect to a voltage at a firstreference electrode also exposed to the first solution sampled and thefirst functionalization layer covers a first working electrode of thefirst electrochemical cell; and wherein the second sensing device is asecond electrochemical cell and wherein the second electricalcharacteristic of the second sensing device is monitored by determininga second voltage change at a second functionalization layer exposed tothe second solution sampled, wherein the second voltage change is withrespect to a voltage at a second reference electrode also exposed to thesecond solution sampled and the second functionalization layer covers asecond working of the second electrochemical cell.
 3. The system ofclaim 1, wherein the first reference electrode is a first on-chipreference electrode separated by a first insulator from the firstworking electrode and the second reference electrode is a second on-chipreference electrode separated by a second insulator from the secondworking electrode.
 4. The system of claim 1, further comprising adding aknown concentration of an analyte to the first solution before samplingthe first solution and adding the same known concentration of theanalyte to the second solution before sampling the second solution. 5.The system of claim 4, wherein the first sensing device is a firstanalyte sensor and the second sensing device is a second analyte sensor.6. The system of claim 5, wherein the first analyte sensor comprises afirst working electrode, a first reference electrode, and a firstcounter electrode.
 7. The system of claim 5, wherein the second analytesensor comprises a second working electrode, a second referenceelectrode, and a second counter electrode.
 8. The system of claim 5,wherein the parameter analyzer is configured to compare the firstelectrical characteristic and the second electrical characteristic bydetermining a difference between the first electrical characteristic andthe second electrical characteristic and wherein the difference betweenthe first electrical characteristic and the second electricalcharacteristic is a result of a difference in the concentration of theanalyte in the first solution sampled and the concentration of theanalyte in the second solution sampled.
 9. The system of claim 1,wherein the first sensing device is a first light-addressablepotentiometric (LAP) sensor and wherein the first electricalcharacteristic of the first sensing device is monitored by: applying afirst bias voltage via a first reference electrode of the first LAPsensor exposed to the first solution sampled; directing a firstmodulated light at a first semiconductor layer of the first LAP sensor;detecting a first photocurrent using a first ammeter coupled to thefirst LAP sensor; and determining a first voltage change at a firstfunctionalization layer of the first LAP sensor exposed to the firstsolution sampled.
 10. The system of claim 1, wherein the second sensingdevice is a second LAP sensor and wherein the second electricalcharacteristic of the second sensing device is monitored by: applying asecond bias voltage via a second reference electrode of the second LAPsensor exposed to the second solution sampled; directing a secondmodulated light at a second semiconductor layer of the second LAPsensor; detecting a second photocurrent using a second ammeter coupledto the first LAP sensor; and determining a second voltage change at asecond functionalization layer of the second LAP sensor exposed to thesecond solution sampled.
 11. The system of claim 1, wherein the firstsurface is a filter surface or a well surface.
 12. The system of claim11, wherein the second surface is separated from the first surface andis another instance of the filter surface or the well surface.
 13. Thesystem of claim 11, wherein the filter surface is configured to trap theinfectious agent on the first surface.
 14. The system of claim 1,wherein at least one of the first surface and the second surface is ahigh-capacity filter.
 15. The system of claim 1, wherein at least one ofthe first surface and the second surface comprises pores of a similarpore size.
 16. The system of claim 1, wherein the parameter analyzer isconfigured to compare the first electrical characteristic with thesecond electrical characteristic by determining a difference between thefirst electrical characteristic and the second electrical characteristicand wherein the difference between the first electrical characteristicand the second electrical characteristic is a result of a difference ina solution characteristic of the first solution and the second solution.17. The system of claim 16, wherein the difference in the solutioncharacteristic of the first solution and the second solution is adifference in at least one of a molecular count, a concentration of anion, and a solution temperature.
 18. The system of claim 1, wherein theinfectious agent is a bacteria, a fungus, a virus, or a prion.
 19. Thesystem of claim 1, wherein at least one of the first sensing device andthe second sensing device is housed by a protective chamber and theprotective chamber is at least one of an electrically isolatedenvironment, a temperature-controlled chamber, and a light-controlledchamber.
 20. The system of claim 1, further comprising a pump configuredto direct the first solution to the first surface or direct the secondsolution to the second surface.
 21. The system of claim 1, wherein thefirst reference electrode is a first external reference electrode andthe second reference electrode is a second external electrode.